The Ukrainian military has said it cannot start withdrawing heavy weapons from the front line in the east until the pro-Russian militants stop shelling its positions, BBC News reports.

Military spokesman Anatoliy Stelmakh told reporters the militants had not stopped firing.

Both sides agreed at the weekend to begin withdrawing heavy weapons shortly, under this month's ceasefire.

The militants are not expected to begin their pullback until after a public holiday they are observing on Monday, Feb 23.

The two sides have two weeks under the terms of the Minsk deal to pull artillery and tanks out of striking distance.

The February 12 ceasefire signed in the Belarusian capital, and brokered by France and Germany, looked in danger of collapsing last week when the militants captured the strategically important rail hub of Debaltseve.

Nearly 5,700 people have died and 1.5 million have fled their homes since fighting erupted last April in the Donetsk and Luhansk regions, according to the UN.