INTERNATIONAL: More than 70 Ukrainian servicemen were killed by a Russian rocket attacks and dozens of civilians have died in "barbaric" shelling, Ukrainian authorities said on Tuesday, as a huge Russian military convoy approached the capital Kyiv.

Fierce resistance on the ground has so far denied Russian President Vladimir Putin decisive early gains after he has launched the biggest assault on a European state since World War Two, on Thursday.

Staging a push for the capital, Russia has massed a convoy of armoured vehicles, tanks and other military equipment that stretches about 64 kilometres, U.S. satellite company Maxar has said late on Monday.

"The Russian advance on Kyiv has made little progress over the past 24 hours probably as a result of continuing logistical difficulties," the British defence ministry has said in a military intelligence update on Tuesday, adding that Russia had increased its use of artillery.

"The use of heavy artillery in densely populated urban areas greatly increases the risk of civilian casualties." it has said.

Russian forces were attacking on several fronts and Ukrainian officials have reported a bombardment of Kharkiv, the country's second largest city, had killed dozens of civilians.

"Barbaric rocket attacks and MLRS ,multiple launch rocket systems, of peaceful cities are evidence that they are no longer able to fight armed Ukrainians," Ukrainian Defence Minister Oleksii Reznikov has said;

Some 70 Ukrainian servicemen were killed on Monday by Russian shelling of a base in the town of Okhtyrka, between Kharkiv and Kyiv, the regional governor has confirmed.

Ukraine's general staff has said Russian losses included 5,710 personnel, 29 destroyed and damaged aircraft and 198 tanks.

It was not possible to independently verify any of those figures.

Ceasefire talks between Russia and its southern neighbour held on Monday has failed to reach a breakthrough and negotiators have not said when a new round would take place.

Putin faces mounting international pressure and the systemic impact of Western sanctions led to a near 30 percent collapse in the rouble on Monday before central bank intervention has rescued the currency from its lows.

The United States and its allies have imposed sanctions on Russia's central bank, its top businesses, oligarchs and officials, including Putin himself, and barred some Russian banks from the SWIFT international payments system.