Shaky Ukraine truce mainly holding

A shaky new truce in Ukraine is already at risk on its second day, with Kiev saying persistent rebel attacks mean there is "no question" of it pulling back heavy weapons.

"There is no question at the moment of us withdrawing heavy weapons" from the frontline because of fire from pro-Russian separatists, a Ukrainian military spokesman, Vladyslav Seleznyov, said on Monday.

Pulling back tanks, artillery and rockets from the frontline in Ukraine's east is scheduled to take place from midnight on Monday (0900 AEDT Tuesday) 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.

The situation around Debaltseve remains "dynamic" after troops repelled several rebel assaults, Seleznyov told a Kiev media conference.

The separatists early on Monday "resumed shelling" and destroyed Debaltseve's police station without causing any casualties, a regional government official, Vyacheslav Abroskin, said on his Facebook page.

Journalists were unable to safely access the town to verify the claims.

Monitors from the Organization for Security and Co-operation in Europe (OSCE) said they would try to get into Debaltseve on Monday after being barred by rebels on Sunday.

Ukraine's foreign minister, Pavlo Klimkin, said during a visit to Bulgaria that "the Ukraine armed forces are fully observing the ceasefire regime but unfortunately in response we have received 112 ... attacks in the past 24 hours from the terrorists of Donetsk and Lugansk".

Another military spokesman, Dmytro Chaly, said at least five Ukrainian soldiers had been killed and 22 wounded by rebel fire in the town of Shyrokine, near the coastal city of Mariupol, since the ceasefire started.

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

Three other Russians, including two MPs, and 14 Ukrainians acting as rebel military or political officials in the self-declared republics of Donetsk and Lugansk were also blacklisted, along with nine entities.

The sanctions were agreed last month but put on hold while France and Germany worked to secure the ceasefire.

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