Ukraine has accused Russia of launching a non-nuclear intercontinental ballistic missile (ICBM) at the central city of Dnipro in what would mark the first ever use of the weapon in combat and a sharp escalation of the conflict.

Kyiv said the nuclear-capable missile had targeted Dnipro, and while the Kremlin declined to confirm it had launched the strike it said it was doing everything possible to avoid a nuclear escalation.

The Russian missile barrage on the industrial city, which authorities said injured two people, is the latest escalation since Ukraine fired Western-supplied long-range missiles on Russia this month.

Ukrainian President Volodymyr Zelenskyy accused Russian leader Vladimir Putin of using Ukraine as a weapons-testing ground. 

In a video posted on social media, Zelenskyy said: "All the characteristics - speed, altitude - correspond to an intercontinental ballistic missile. Expert examinations are underway. It is obvious that Putin is using Ukraine as a testing ground."

ICBMs are designed to carry nuclear warheads and have a minimum range of 5,500 kilometers (3,400 miles).

The Ukrainian air force said in a statement that Russia had launched several types of missiles at Dnipro, targeting critical infrastructure hours on Thursday.

"In particular, an intercontinental ballistic missile was launched from the Astrakhan region of the Russian Federation," the statement said.

A source in the Ukrainian air force confirmed to AFP it was the first time such a weapon had been used by Russia since February 2022. 

Sources and experts told AFP, however, it was "obvious" the missile that struck Ukraine did not carry a nuclear charge, which indicates Russia launched it mainly for political effect.

Asked whether Moscow fired the missile, Kremlin spokesman Dmitry Peskov said he had "nothing to say on this topic".

He did however say the Kremlin was making a "maximum effort" to avoid a nuclear conflict, after it updated its nuclear doctrine this week.

The new policy allows Moscow to use nuclear weapons against non-nuclear states and Russia said the move should be seen as a warning to the West.

"We have stressed in the context of our doctrine that Russia is taking a responsible position to make maximum effort not to allow such a conflict," Peskov added.

While Moscow declined to comment on the attack, the Russian foreign ministry spokeswoman received a phone call during a live press briefing, in which she was ordered not to comment on reports of the ballistic strike, video showed.

'Masha,' an unknown male voice on the phone said, addressing spokeswoman Maria Zakharova. "On the Yuzhmash ballistic missile strike that the Westerners have started talking about, we are not commenting at all."

Yuzhmash is the Russian name of an aerospace manufacturer in Dnipro  - now called Pivdenmash - that produced missiles during the Soviet Union and is reported now to produce satellites.

The EU said the attack, if confirmed, would mark a "clear escalation" by Putin. "While we're assessing the full facts it's obvious that such (an) attack would mark yet another clear escalation from the side of Putin," foreign affairs spokesman Peter Stano told reporters.

The UK meanwhile said the strike would be "reckless and escalatory".

Ukrainian air defense units downed six missiles, the air force said, without elaborating on whether the ICBM was among those.

Fabian Hoffmann, a research fellow at the University of Oslo, who specializes in missile technology, said Russia could have used other types of missiles - or even drones - for such an attack.

"This is all about the political effect. This is not about the military value," Hoffmann told AFP.

Russia and Ukraine have escalated their use of deadly long-range missiles over recent days since the United States gave permission to use its ATACMS (Army Tactical Missile System) against military targets inside Russia - a long-standing Ukrainian request.

British media meanwhile reported on Wednesday that Kyiv had launched UK-supplied Storm Shadow missiles at targets in Russia after being given the green light from London. 

The defense ministry in Moscow said on Thursday its air defense systems had downed two Storm Shadows, without saying whether they were downed on Russian territory or in occupied Ukraine. 

The missile escalation is coming at a critical moment on the ground for Ukraine, as its defensive lines buckle under mounting Russian pressure across the sprawling front line.

Russia also on Thursday claimed deeper advances in the war-battered Donetsk region, announcing its forces had captured another village close to Kurakhove, closing in on the town after months of steady advances.