Pro-Russian separatists in eastern Ukraine have denied reports they have fled their stronghold of Sloviansk.Ukraine's interior minister said a large number of rebels had left but admitted other fighters remained.Ukrainian forces launched an offensive against the separatists this week after a 10-day ceasefire broke down.Ukrainian President Petro Poroshenko has said he is ready to return to a ceasefire but there has been no confirmation of any new talks.ConvoyInterior Minister Arsen Avakov said on Facebook that a large number of insurgents had left Sloviansk but that other fighters were still in the town.Mr Poroshenko has ordered the military to hoist the Ukrainian flag over the city council building, a statement from the presidency says.Mr Avakov said "some intelligence suggests" that the military commander of the self-declared Donetsk Peoples' Republic (DPR), Igor Strelkov, was among those leaving, but this has not been confirmed.The commander, whose real name is Igor Girkin, is accused by Ukraine's government and the European Union of being a Russian military intelligence officer.A spokesman for the DPR denied the separatists had left the town.Ukrainian military spokesperson Alexei Dmitroshkovskiy also told the BBC the town was still in rebel hands.However, the chief of Ukraine's general staff told President Poroshenko that a group of militants had tried to break out of Sloviansk and had come under mortar fire from the armed forces, a presidential statement said.The Ukrainian Ostrov website quoted hostages who said they had managed to free themselves from detention in Sloviansk's main police station. They also reported that separatists had left towards Kramatorsk.In a separate development, Russian news agency Interfax reported that Ukrainian forces had destroyed the headquarters of the DPR in the town of Artemivsk.Diplomatic movesThere has been intense diplomatic activity this week to try to reinstate the ceasefire, with telephone calls involving Germany, France, the US, Russia and Ukraine.Mr Poroshenko said he was ready to return to a ceasefire provided it was observed by both sides, all hostages were freed and borders secured by government forces.Ukrainian officials said on Friday they had proposed indirect talks with rebel leaders but were still waiting for a response.Russian President Vladimir Putin was urged to use his influence to put pressure on the rebels in the Donetsk and Luhansk regions.Mr Putin in turn said he was "deeply concerned about the rise in deaths among the civilian population and sharp increase in refugees" entering Russia from south-eastern Ukraine.Mr Poroshenko called off a unilateral truce on 30 June, accusing the rebels of staging deadly attacks on Ukrainian government troops.Violence erupted in eastern Ukraine in April, when the separatists declared independence in the Donetsk and Luhansk regions.That followed Russia's annexation of Ukraine's Crimea.The current Ukraine crisis started last November, when then President Viktor Yanukovych decided, under pressure from Russia, not to sign an agreement with the EU, leading to street protests in Kiev and his eventual overthrow.President Poroshenko signed the free trade part of the EU deal in Brussels on 27 June, after earlier signing the political co-operation clauses. (BBC)ANN.Az