Russia's military action in Ukraine has entered a fourth day

• Ukraine will send a delegation to the border with Belarus for talks with Russia

• Russian president Vladimir Putin has ordered strategic deterrence forces, including nuclear units onto alert

• The EU has announced it will ban Russian flights and block state broadcasters

• Energy company BP is selling its 20% state in Russia's Rosneft, citing the situation in Ukraine

• Major oil and gas infrastructure was struck overnight, sparking fierce fires. Battles are continuing across the country

• A UN agency says 64 civilians have died and 174 have been injured since Russian troops crossed the border

• China's Wang Yi has said sanctions will not solve the crisis and described unilateral measures as illegal

• German Chancellor Olaf Scholz announced an increase in military spending as he characterized conflict as "might" against "right"

• UAE advisor says the country will not take sides in the conflict

• Belgium and Finland have become the latest EU countries to announce they will close their airspace to Russian flights

Ukraine will send a delegation to its border with Belarus to meet with Russian officials for talks.

It had previously declined invitations from Belarus' president Alexander Lukashenko on the grounds that his country was aiding the Russian offensive, but changed tack after receiving assurances that Minsk would refrain from any military activity while the discussions continue.

Ukrainian foreign minister Dmytro Kuleba said the fact that Russia was willing to talk without preconditions was "already a victory" for Kyiv but insisted not one inch of territory would be surrendered.

Ahead of the talks, Zelenskyy confessed that he did not have "high hopes" but said he was willing to try to find a solution.

High alert

Russia's deterrence forces, which include nuclear-armed units, have been put on high alert as tensions rise with the U.S. and its NATO allies. NATO has been been bolstering its forces in eastern Europe and supplying weapons to Ukraine. In addition, many western countries have imposed sanctions on Moscow, which Putin says are illegal.

As he announced his military operation, Putin had warned third countries not to intervene - or risk facing never-seen-before consequences.

However today he suggested those warnings had not been heeded.

"As you can see, not only do Western countries take unfriendly measures against our country in the economic dimension - I mean the illegal sanctions that everyone knows about very well - but also the top officials of leading NATO countries allow themselves to make aggressive statements with regards to our country," Putin said on state television.

Russia has the world's largest nuclear arsenal while Ukraine gave up its own atomic weapons when it gained independence from the Soviet Union.

NATO secretary general Jens Stoltenberg described Putin's statement as "dangerous rhetoric" and said the Russian leader was behaving "irresponsibly".

Street fighting

The Ukrainian military has posted images which it says show destroyed Russian military vehicles on the streets of Kharkiv, a city of nearly 1.5 million people near Ukraine's border with Russia.

Fighting is taking place on the streets they say, with the regional governor claiming the attackers had been forced back.  The development would mark a change in Russia tactics as troops have previously avoided most large population centers. 

Nevertheless, the flow of refugees westwards has continued, with CGTN reporters documenting regular arrivals of women and children on foot at the borders with Hungary and Poland, adding to 368,000 people that the Ukrainians say have left the country since Thursday.

As fighting continues, an oil storage installation near the capital Kyiv was set ablaze overnight, lighting up the night sky. The site is near a Ukrainian military airbase. The authorities in the breakaway People's Republic of Luhansk say one of their fuel depots has also been struck.

Both sides claim their forces are on top. President Putin, in a speech to mark Special Forces Day, praised his troops.

"Special gratitude to those who these days are heroically fulfilling their military duty in the course of a special operation to provide assistance to the People's Republics of Donbas," he said in a televised address.

Meanwhile, in a video filmed on the streets of Kyiv, his Ukrainian counterpart said the military was holding back the invading army.

"We have withstood and successful repelled enemy attacks," Zelenskyy said in a video message. "The fighting continues in many cities and districts of our state. We are defending our country, the land of our future children."

International responses

China has urged the international community not to impose "unilateral and illegal" sanctions on Russia as it pushes for a diplomatic solution to the crisis. In a call with German foreign minister Annalena Baerbock, China's Wang Yi called for an emphasis on promoting talks. Russia's legitimate security concerns regarding the eastward expansion of NATO need to been addressed, he added.

An advisor to the UAE's president said the country was not taking sides in the conflict with an aim to pushing a political solution. Anwar Gargash, a senior diplomatic advisor to the UAE's President Khalifa Bin Zayed Al-Nahyan, made the comments on Twitter after his country joined China and India in abstaining from a UN security council motion calling on Moscow to withdraw from Ukraine. Russia vetoed the motion.

Belarus' Lukashenko has renewed an offer to Ukraine to host talks with Russia, which Kyiv had previously rejected on the grounds that Minsk had helped support Russia's military. Zelenskyy layer said he had spoken with Lukashenko, while declining to elaborate. Russian news agency Tass then cited an anonymous Belarusian official as saying Ukraine would send representatives to the country.

European reaction

European Union countries have continued to add to measures designed to hurt the Russian economy. European Commission president Ursula von der Leyen announced that all Russian aircraft, including private planes, would be refused permission to fly over the bloc. In addition, state broadcasters RT and their subsidiaries will be banned from all EU countries, she said, without explaining how this would be done.

Belarus will also be subject to sanctions because of its support for the Russian military, Von der Leyen told a news conference.

Earlier in the day, in a speech to his country's parliament, German Chancellor Olaf Scholz announced a sharp increase in defense spending to meet the NATO target of 2 percent of GDP. Describing Putin as a "warmonger" he said the world must decide "whether might can break right". However he insisted he would not close the door to talks with Moscow to end the conflict.

The UK's foreign secretary Liz Truss said that no talks with Russia should take place until it had removed it's military from Ukrainian territory.

In a statement on its website, Energy giant BP said it will sell its 20% state in Russia's state oil and gas company Rosneft.

"BP has operated in Russia for over 30 years, working with brilliant Russian colleagues. However, this military action represents a fundamental change. It has led the BP board to conclude, after a thorough process, that our involvement with Rosneft, a state-owned enterprise, simply cannot continue," chair Helge Lund said.