On Wednesday, Ukrainian President Petro Poroshenko called the ceasefire the first step of a peace plan that would also include an amnesty and constitutional amendments that give more power to the regions. However, Poroshenko did not say when he would implement the plan to quell nearly two months of rebellion in eastern Ukraine.

Poroshenko, a 48-year-old confectionery tycoon elected president on May 25, told journalists in Kyiv that the insurgents would have to disarm and reinstate order in the regions "in a very short time," according to the Interfax Ukraine news agency. "Immediately afterwards, we must receive support for the peace plan from all sides," the president said on Wednesday.

Poroshenko had earlier discussed the plan in telephone conversations with Russian President Vladimir Putin and German Chancellor Angela Merkel, according to his office. Merkel chancellor has also asked Putin to use his influence to calm the rebellion in eastern Ukraine.

On Wednesday, Poroshenko also proposed Pavlo Klimkin, Ukraine's ambassador to Germany, as the country's foreign minister.

'Caused by sabotage'

Vitaly Markelov, Gazprom's deputy chief executive, told reporters on Wednesday that an explosion on the Russian oil monopoly's pipeline through Ukraine had not disrupted flows to the European Union. Markelov refused to speculate on the cause of the explosion, but said that poor maintenance of pipelines in Ukraine increased the likelihood of such accidents.

"I think they will continue to occur because the network needs to be maintained well," he said.

Ukrainian officials have not ruled out terrorism as the cause of the explosion. The Energy Ministry has linked the blast to the halt of gas supplies to Ukraine.

In a statement released Wednesday, the ministry announced that it had "grounds to believe" that "the blast was caused by sabotage" intended to discredit Ukraine as a transit country. However, the ministry did not provide any evidence to support the claim.

The blast, which occurred Tuesday far from where government troops have fought separatists, came a day after Russia cut gas supplies to Ukraine in a dispute over price and overdue payments. Russian officials say Ukraine must pay at least $1.9 billion (1.4 billion euros) of the $4.5 billion the country owes before talks on clearing the debt and agreeing on prices could resume. On Monday, Gazprom had announced that it would need to start pumping by mid-October to insure adequate winter supplies for Ukraine.

mkg/ rg(Reuters, AFP, dpa, AP)