The proposed summit was announced in Washington and Paris hours after the United States issued a fresh warning that Russian forces were poised for an attack on Ukraine within days.

Putin said the Kremlin’s chief concerns remained unanswered – guarantees from the West that NATO would expand no further and that Ukraine would never be permitted to join.

Moscow has repeatedly denied it has any intention of invading Ukraine but has held several rounds of talks with Western countries and NATO on its demand for “security guarantees“ that the Atlantic alliance will expand no further and Ukraine will never become a member.

In his third conversation with the Russian president in two months,  Biden said Washington would respond "decisively and impose swift and severe costs" if Russia moved into Ukraine.

The ex-Soviet state is on the EU list of countries to be considered to ensure energy supplies for the 27-nation bloc.

Western estimates put at about 30,000 the number of Russian troops taking part in the exercises – along with most of the Belarusian army.

Lukashenko’s support for Moscow stands in contrast with the neutrality he sought to adopt eight years ago when Russia seized the Crimean Peninsula from Ukraine and fomented a separatist revolt in Ukraine’s eastern Donbas region.

Sources at SOCAR told the Tribune that they viewed the talks with Hungary as a means of soothing European Union concerns that Budapest was significantly boosting shipments of Russian gas.

But Putin also said he hoped diplomatic initiatives would proceed. The comments were his first public pronouncements since the New Year.

Stable gas supplies remain at the top of the agenda – gas prices have soared past $1,000-$1,300 per thousand cubic metres and oil futures now top $93 a barrel.