Ukraine will only negotiate with the rebels once they lay down their arms, Kiev's defence minister has said.

乌克兰国防部长称，乌克兰政府不会与造反派进行谈判，除非他们放下武器。

"There will be no more unilateral ceasefires" by Ukrainian troops, Valeriy Heletey said in a statement posted on the ministry's website.

He was speaking after separatists fled their eastern strongholds and regrouped in the regional centre of Donetsk.

Ukrainian forces recaptured several cities after President Petro Poroshenko brought an end to a 10-day ceasefire.

He has since ordered the army to blockade the insurgents inside the two cities of Donetsk and Luhansk. On Tuesday he named a new anti-terror chief, Vasyl Grytsak.

Mr Poroshenko had promised ceasefire talks no later than last Saturday, but that was before the series of recent military successes.

The latest ceasefire expired at the end of June and failed to lead to any negotiated settlement.