Ukrainian forces are preparing for new Russian attacks in the east of the country as Moscow deploys more troops there after suffering setbacks near the capital Kyiv, President Volodymyr Zelensky said on Thursday.

Russia's invasion of its neighbour, now in its fifth week, has driven more than 3.5 million people from their homes, killed thousands, sent global oil prices soaring and brought Russian-Western tensions to their worst point since the Cold War.

The United States is considering a massive release of oil reserves to counter rising oil prices which are fuelling inflationary fears around the world. The International Energy Agency (IAE) will hold an emergency meeting on Friday.

Tough resistance by Ukrainian forces has prevented Russia from capturing any major city, including Kyiv, where a Russian armed column was held back for weeks.

The head of Britain's GCHQ spy service said new intelligence showed some Russian soldiers had refused to carry out orders, sabotaged their own equipment and accidentally shot down one of their own aircraft.

In an early morning video address, Zelensky referred to Russian troop movements away from Kyiv and Chernihiv and said that was not a withdrawal but rather "the consequence of our defenders' work."

Zelensky added that Ukraine is seeing "a build-up of Russian forces for new strikes on the Donbas and we are preparing for that."

Russia says its forces are regrouping to focus on "liberating" the breakaway eastern Donbas region.

The United States is considering a massive release of oil reserves to counter rising oil prices which are fuelling inflationary fears around the world. The International Energy Agency (IAE) will hold an emergency meeting on Friday.

Tough resistance by Ukrainian forces has prevented Russia from capturing any major city, including Kyiv, where a Russian armed column was held back for weeks.

The head of Britain's GCHQ spy service said new intelligence showed some Russian soldiers had refused to carry out orders, sabotaged their own equipment and accidentally shot down one of their own aircraft.

In an early morning video address, Zelenskiy referred to Russian troop movements away from Kyiv and Chernihiv and said that was not a withdrawal but rather "the consequence of our defenders' work."

Zelensky added that Ukraine is seeing "a build-up of Russian forces for new strikes on the Donbas and we are preparing for that."

Russia says its forces are regrouping to focus on "liberating" the breakaway eastern Donbas region