The top diplomats from the UK, US, France, Germany and Ukraine have postponed a plan to meet in London on Wednesday for high-level talks on how to end Russia's war.

Axar.az reports, citing Sky News, discussions will instead take place among senior officials from the five nations, though the Ukrainian foreign minister is also still due to be in the capital and will hold a bilateral meeting with David Lammy, it is understood.

The downgrading in the level of diplomacy is in contrast with an intensification in the pressure from Donald Trump and his team for Kyiv and Moscow to agree a ceasefire.

A US peace proposal that is due to be discussed in London would see the United States recognise Russia's illegal annexation of Crimea - something rejected by Volodymyr Zelenskyy on Tuesday.