A shaky new truce in Ukraine was already at risk on its second day Monday as Kiev said there was "no question" of its troops pulling back heavy weapons, and the EU ratcheted up sanctions on Russia.

A shaky new truce in Ukraine was already at risk on its second day Monday as Kiev said there was "no question" of its troops pulling back heavy weapons, and the EU ratcheted up sanctions on Russia.

"There is no question at the moment of us withdrawing heavy weapons" from the frontline because of persistent attacks by pro-Russian rebels, a Ukrainian military spokesman, Vladyslav Seleznyov, told AFP.

Pulling back tanks, artillery and rockets from the frontline in Ukraine's east is meant to take place from midnight (2200 GMT) on Monday as the second phase of a European-mediated truce agreed last week.

But while OSCE monitors said the ceasefire that came into effect on Sunday was being generally followed, shelling was unabated around Debaltseve, a strategic railway hub linking the two main rebel-held cities of Donestk and Lugansk.

Thousands of government troops are in the hotspot town, mostly surrounded by pro-Russian separatists.

While tensions rose on the ground, the European Union upped the ante on the diplomatic front, adding two Russian deputy defense ministers, Anatoly Antonov and Arkady Bakhin, to its travel-ban and asset-freeze blacklist for allegedly sending Russian troops and materiel in to Ukraine to support the insurgency.

Russia has denied repeated allegations it has sent troops and tanks to support the pro-Russian separatists. The West, though, has imposed sanctions that, along with the sharp decline in oil prices, are accelerating the Russian economy's slide into recession.

Russian President Vladimir Putin has said he has committed to the peace deal that ultimately aims to end the bitter Ukraine conflict that has claimed more than 5,000 lives since it started in April last year, and has sent East-West relations to lows not seen since the Cold War.