German Chancellor Angela Merkel said in Berlin that new sanctions could be applied if efforts to stabilise the situation were not speeded up.

UK Foreign Secretary William Hague said inaction by Russia would mean a stronger case for sanctions.

President Petro Poroshenko said violations might end the truce.

However, his Foreign Minister, Pavlo Klimkin, told reporters at a Nato meeting in Brussels on Wednesday that Ukraine would “stick to our unilateral ceasefire,” which began on Friday.

On Tuesday, a Ukrainian military helicopter was shot down with the loss of nine lives, with reports of fighting overnight near the Russian border in Luhansk region.

The Ukrainian military accused the rebels on Wednesday of breaking the ceasefire 44 times since it began.

But Alexander Borodai, prime minister of the self-styled Donetsk People’s Republic, has said there is effectively no ceasefire because of government attacks.

The truce is part of Ukraine’s plan to end two months of conflict with pro-Russian insurgents who control key buildings in towns and cities across the east.

More than 420 people have been killed in the region since mid-April, the UN estimates.

Source: BBC.co.uk