* Poroshenko does not rule out talks with foes
* Russia-Ukraine gas talks stall in Brussels
* Rebels sceptical of Poroshenko's intentions (Adds Poroshenko calls with Biden, paragraphs 10-11)
By Timothy Heritage
KIEV, June 11 (Reuters) - Ukraine's new president signalled on Wednesday he would be ready to hold talks with opponents in eastern Ukraine if pro-Russian separatists waging an insurgency there agreed to lay down their weapons.
The rebels show no sign of giving up their arms, but opening talks would be a big step on the road to peace, building on Ukrainian President Petro Poroshenko's meetings this week with Moscow's envoy and with Russian President Vladimir Putin in France last week.
Poroshenko, trying to act swiftly after being sworn in as president on Saturday, was quoted by his press office as telling the governor of the Donetsk region of east Ukraine that he would not rule out holding "roundtable" talks with "different parties".
"We do not need negotiations for the sake of negotiations. Our peace plan must become the basis for further de-escalation of the conflict," a statement on the president's website quoted Poroshenko as saying at a meeting with Governor Serhiy Taruta.
He added: "Terrorists must lay down their weapons."
Donetsk is at the heart of the rebellion by separatists who oppose centralized rule from the national capital, Kiev, and want Russia to annex parts of the mainly Russian-speaking east - as it did the Black Sea peninsula of Crimea in March.
Taruta, one of the country's richest men, was brought in by Kiev to try to keep the eastern regions within Ukraine soon after Poroshenko's predecessor was ousted following months of protests and fled to Russia in February.
The meeting with Taruta was Poroshenko's latest attempt to win backing for peace proposals he announced on taking office but without offering details.
He has also said that before making any foreign trips as president, he will visit the Donbass coal-mining area, where Donetsk is the main city. A political source in Kiev confirmed plans were under way for a visit and it was likely to be to Donetsk.
Poroshenko talked by telephone on Tuesday and Wednesday with U.S. Vice President Joe Biden, who applauded the Ukrainian leader's commitment to implementing his peace proposal, the White House said.
It added in a statement that Biden "underscored that de-escalation depends on Russia's recognizing President Poroshenko as the legitimate leader of Ukraine, ceasing support for separatists in eastern Ukraine, and stopping the provision of arms and materiel across the border."
NATGAS TALKS STALL
Poroshenko's moves this week have given new momentum to peace efforts, although talks on ending a dispute with Moscow over the price Kiev pays for Russian natural gas, as well as billions of dollars in unpaid bills, stalled on Wednesday.
Moscow has threatened to cut off gas supplies to Ukraine if no deal is reached by Monday and that could disrupt deliveries to the European Union, which gets about a third of its gas imports from Russia, half of them via Ukraine.
Poroshenko's office says progress is being made at talks with Russia's ambassador to Kiev, but the president's proposals have been unanswered by the rebels in east Ukraine, where scores of people have been killed in fighting since April.
The violence has continued, particularly around the rebel-held city of Slaviansk and nearby Semyonovka, although there were no reports of fierce clashes on Wednesday.
Ukraine's health minister said 210 people had been brought to morgues in the Donbass area since the clashes began, including 14 children, but did not say whether they were killed in the fighting.
Poroshenko, who met Putin for 15 minutes during World War Two anniversary events in Normandy on the eve of his inauguration, wants corridors opened to let rebel fighters escape to Russia and to allow civilians to escape the fighting.
Russia denies any involvement in the uprising and says the onus for ending the violence must be on Kiev, whose forces have launched a military operation against the separatists.
Russian Foreign Minister Sergei Lavrov told U.S. Secretary of State John Kerry by telephone it was vital to hold direct talks between the Ukrainian government and the rebels.
Lavrov "underscored the need for the swiftest halt by Kiev of its military operation ... agreement on terms of a ceasefire, a solution to acute humanitarian issues and ... real national dialogue on Ukraine's future structure," his ministry said.
Many civilians and rebels doubt Poroshenko can carry out his promises to secure peace, and some question his aims.
"The day Poroshenko proposed his humanitarian corridor, his troops were firing on Slaviansk and Semyonovka. How can we trust the word of someone like that?" said a rebel who gave his name only as Alexander as he ate a lunch of rice and chicken on the ground floor of the occupied administration building in Donetsk.
(Additional reporting by Thomas Grove in Donetsk, Pavel Polityuk in Kiev, Steve Gutterman in Moscow, and Jeff Mason in Washington; Editing by G Crosse and Peter Cooney)
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