MUNICH, Germany (AFP) - US Vice-President Joe Biden on Saturday launched a passionate plea to Vladimir Putin to show by his actions that the Russian leader desires peace in Ukraine.

His words came as Kiev on Saturday accused pro-Russian Ukrainian separatists of massing forces for fresh offensives, with seven civilians and five soldiers killed in the latest fighting in the east.

"Given Russia's recent history, we need to judge its deeds not its words. Don't tell us, show us, President Putin," Biden told a global security conference in Munich, shortly after the Russian leader said Moscow did not want war.

While he did not directly say that Washington would provide arms to Kiev, Biden insisted Ukraine had the right to defend itself from pro-Russian separatists waging war in the east.

Washington would continue to aid Kiev, Biden pledged, adding "too many times President Putin has promised peace and delivered tanks and troops and weapons".

"So we will continue to provide Ukraine with security assistance. Not to encourage war but to allow Ukraine to defend itself."

"Let me be clear: We do not believe there is a military solution in Ukraine," Biden told the Munich conference.

"But let me be equally clear: We do not believe Russia has the right to do what they're doing.

"We believe we should attempt an honourable peace. We also believe the Ukrainian people have a right to defend themselves," the American Vice-President added, winning applause from the audience.

On Saturday, Ukrainian defence official Volodymyr Polyovyi told journalists that rebels were "accumulating forces for further offensive operations on Debaltseve and Mariupol."

The separatists were sending fresh tanks, armoured personnel carriers as well as multiple launch rocket systems to the Debaltseve region and Granitne, around 35km north-east of Mariupol, Polyovyi said.

Debaltseve - mid-way between rebel centres Donetsk and Lugansk - has been the focus of fierce fighting for over a week as insurgent fighters try to encircle government troops holding the strategic railway hub.

Separatist fighters in January fired rockets at the strategic government-held port city of Mariupol, whose capture could open up a land bridge from Russia to Crimea.

On Thursday, German Chancellor Angela Merkel and French President Francois Hollande flew to Kiev to put a new peace plan to Ukrainian President Petro Poroshenko.

According to Ukrainian online news site theinsider.ua, Merkel and Hollande proposed that Kiev pull its forces from Debaltseve in exchange for rebels pulling back their troops from near Mariupol.

Poroshenko rejected the proposal, the website said, citing sources close to the presidency.

Officials from the two warring sides said that over the past 24 hours six civilians were killed by shelling across government-held territory while one local resident died in rebel bastion Donetsk.

The latest toll includes two women killed by shelling in government-controlled Avdiyivka, just north of Donetsk airport, Kiev-loyal regional police chief Vyacheslav Abroskin said.

Clashes with pro-Moscow insurgents over the same period claimed the lives of five government soldiers and wounded 26 more, Ukraine's military said.

Missile fire on Saturday hit Debaltseve a day after a brief truce allowed hundreds of civilians to flee, government officials said.

Ukraine's military had previously said that a temporary ceasefire that saw shelling of the beleaguered town halt for several hours Friday could be extended into Saturday.

A separatist military spokesman said Saturday that the insurgents were not planning to dispatch any more buses to evacuate civilians due to safety concerns.

Only some 40 people opted to head to the rebel side Friday.

Amnesty International said earlier this week that most of the town's former population of 25,000 had fled, but that around 7,000 civilians remain behind.

An AFP journalist in the main rebel city of Donetsk said that the sounds of heavy explosion could be heard around the city Saturday.

Some 5,400 people have been killed by fighting since the start of the conflict in April, according to the United Nations.