HEADLINES

• Airstrikes rock Ukraine's strategic Black Sea port, Odesa, Sunday morning, but the army says there were no casualties. "High-precision sea and air-based missiles destroyed an oil refinery and three storage facilities for fuel and lubricants near the city of Odesa," the Russian defense ministry says.

• Russian troops leave scenes of devastation in the city of Bucha, just outside Kyiv, where nearly 300 people have been buried in a mass grave, mayor Anatoly Fedoruk tells AFP. The heavily destroyed city is littered with corpses, with 20 bodies in civilian clothing strewn across a single street. 

• Russia's defense ministry has denied the claims by Kyiv that its forces carried out the mass murder of civilians in Bucha, RIA news agency reports. The Ukraine Ministry of Foreign Affairs shared photographs of dead bodies with CGTN Europe, some showing the victims with their hands tied and others of burned bodies. We have been unable to verify the source of the photographs but they match similar photographs taken by AFP journalists in Bucha.

• Ukrainian Foreign Minister Dmytro Kuleba accused Russia of carrying out a deliberate "massacre" in Bucha outside Kyiv. Human Rights Watch said it had documented what it described as "apparent war crimes" committed by Russian military forces against civilians in Ukraine.

• Ukraine has regained control of "the whole Kyiv region" after invading Russian forces retreated from some critical towns near the Ukrainian capital, deputy defense minister Ganna Maliar says. "Russia is prioritizing a different tactic: falling back on the east and south," according to a Ukrainian presidential adviser.

• The Red Cross says its team left for the besieged southern port of Mariupol Saturday for a new evacuation effort. 

• The Kremlin said that Russia would ask for ruble payments for other exports, and the West's sanctions have accelerated the erosion of confidence in the U.S. dollar and the euro.

• Ukraine's top negotiator in peace talks with Russia says that Moscow had "verbally" agreed to key Ukrainian proposals, raising hopes that talks to end fighting are moving forward.

• Russia will achieve all of the aims of its "special military operation" in Ukraine and hopes that Moscow and Kyiv can ultimately sign some sort of peace deal, the Kremlin said, Interfax news agency reported.

• Russian police detain 211 people at protests against Moscow's military operation in Ukraine, according to OVD-Info, a Non-Governmental Organization.

• The number of refugees fleeing Ukraine has passed 4.1 million, the United Nations says.

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IN DETAIL 

Explosions rocked the strategic Ukrainian port city of Odesa on Sunday as a top UN official headed to Moscow to try to secure a "humanitarian ceasefire" after evidence emerged of possible civilian killings around Kyiv.

Thick plumes of black smoke rose from several areas on the historic Black Sea port after airstrikes shook the city at about 6:00 am (0300 GMT), but the Ukrainian army said no one was killed. Russia's defense ministry confirmed the attack, saying "high-precision sea and air-based missiles destroyed an oil refinery and three storage facilities for fuel and lubricants."

The ministry claimed the targets were supplying fuel to Ukrainian troops. Anton Herashchenko, an adviser to the Ukrainian interior minister, said: "Fires were reported in some areas. Some of the missiles were shot down by air defense."

The strikes came with Greece's Foreign Minister Nikos Dendias expected in the city to deliver humanitarian aid to the municipal authorities.

UN chief Antonio Guterres' humanitarian envoy Martin Griffiths was meanwhile seeking a halt in the fighting. He will fly on to Kyiv from Moscow. On Saturday, both Russia and Ukraine agreed to meet him, Guterres said.

WATCH: Iolo ap Dafydd reports from Ukraine

'Mass graves' in Bucha

In the ravaged city of Bucha, just outside the Ukrainian capital, the bodies of nearly 300 civilians were found in mass graves after Russian troops withdrew, according to the local mayor. AFP reporters saw at least 20 bodies strewn across a single street, all in civilian clothing. One had his hands tied behind his back with a white cloth and his Ukrainian passport left open beside his body.

"All these people were shot," Bucha's mayor Anatoly Fedoruk said, adding that 280 other bodies had been buried in mass graves in the town. "These are the consequences of Russian occupation."

The International Criminal Court has already opened a probe into possible war crimes committed in Ukraine. Several Western leaders, including U.S. President Joe Biden, have accused Putin of being a "war criminal."

Russia's defense ministry said its forces did not kill civilians in Bucha, "During the time this settlement was under the control of Russian armed forces, not a single local resident suffered from any violent actions." In a statement the ministry said Russia's military delivered 452 tonnes of humanitarian aid to civilians there. 

The President of the European Commission, Ursula von der Leyen, was "appalled by reports of unspeakable horrors in areas from which Russia is withdrawing," and called for an independent investigation to ensure the "perpetrators of war crimes will be held accountable."

'Verbal agreement' 

Pope Francis, on a visit to the Mediterranean island of Malta, issued a thinly veiled attack on Putin for ordering troops into Ukraine and on Sunday made a plea for refugees fleeing the conflict to be welcomed.

The pontiff has not ruled out a visit to Kyiv.

On talks to end the fighting, Ukrainian negotiator David Arakhamia told local television channels that Russia had "verbally" accepted most of Kyiv's proposals - except on the issue of Crimea, which Moscow annexed in 2014.

Among the agreed-upon points was that a referendum on Ukraine's neutral status "will be the only way out of this situation," Arakhamia said. He said any meeting between Zelenskyy and Putin would "with a high probability" take place in Turkey, which has sought to mediate the conflict.

As Russian forces withdraw from some northern areas, Moscow appears to be focusing on eastern and southern Ukraine, where it already holds vast swathes of territory. UK defense intelligence said that Russian air activity in the last week had been concentrating on southeastern Ukraine, "likely as a result of Russia focusing its military operations in this area."

But it said Russia was struggling to find and destroy air systems, which has "significantly affected their ability to support the advance of their ground forces." In his latest video message, Zelenskyy said Russian troops wanted to seize the disputed Donbas region and the south of Ukraine, promising "to defend our freedom, our land and our people."

Ukrainian presidential adviser Mykhaylo Podolyak warned on social media that "without heavy weapons we won't be able to drive (Russia) out."

Resistance in Mariupol 

Russia's efforts to consolidate its hold on southern and eastern areas of Ukraine have been hampered by the resistance of Mariupol despite devastating attacks lasting weeks. At least 5,000 residents have been killed in the besieged southern port city, according to officials, while the estimated 160,000 who remain face shortages of food, water, and electricity.

The International Committee of the Red Cross said its team left for Mariupol on Saturday to make another attempt at conducting an evacuation after being forced to turn back the day before.

In another southern city, Enerhodar, which is under Russian control, a Ukrainian official said Russian forces opened fire on peaceful demonstrators, injuring four. Zelenskyy has thanked the residents of Enerhodar, the site of Europe's largest nuclear power plant, which had been seized by Russian troops in early March, for their bravery.

"When people protest, and the more they protest, the harder it is for the occupiers to destroy us, to destroy our freedom," Zelenskyy said.

In Russia, hundreds of people gathered across the country on Saturday to protest against the war in Ukraine. Police detained 211 people in several cities, according to OVD-Info, a group that monitors arrests.