Ukraine claims rebels flushed from main stronghold

Kiev: Ukraine's interior minister said on Saturday that most pro-Russian rebels and their top commander had fled their main eastern stronghold in what would be Kiev's biggest success of the nearly three-month campaign.

"This morning, intelligence reported that Girkin (Igor Strelkov) and a substantial part of the rebels had fled Slavyansk," Ukraine's Interior Minister Arsen Avakov said in reference to the industrial city of nearly 120,000 the insurgents captured on April 6.

Ukraine alleges that Strelkov is a colonel in Russia's military intelligence unit know as the Chief Intelligence Directorate (GRU).

Both Strelkov and Moscow deny any GRU link despite Western claims that the Kremlin is covertly funding and arming the uprising to destabilise Kiev's new pro-European leaders and retain control over over Russia-speaking eastern regions of Ukraine.

Avakov said in a Facebook post that the militias were fleeing to Gorlivka - a city of 260,000 about 50 kilometre southeast of Slavyansk that also remains largely under the militias' control.

He wrote in a later post that civilians were taking over roadblocks previously controlled by the insurgents "and carrying weapons and bulletproof vests abandoned by the rebels".

A Human Rights Watch observer who said she was in the area confirmed Avakov's claim in a tweet.

"Between 8 and 9 this morning saw insurgents leaving #Slavyansk via #Kramatorsk," Tatyana Lokshina said in a post.

"They were saying, 'the city's fallen, everyone's getting out'," she wrote.

Strelkov himself told the pro-Kremlin Life News channel on Friday that his units "will be destroyed... Within a week, two weeks at the latest" unless Russia helped secure an immediate truce or moved in its troops.

Slavyansk is the symbolic heart of an uprising sparked by the February ouster of a pro-Kremlin administration in Kiev and fuelled by Russia's subsequent seizure of Crimea.

Relentless shelling and sniper fire have since killed more than 470 people and left Western leaders frustrated by repeated mediation failures.

Ukrainian President Petro Poroshenko on Friday agreed to immediate crisis talks with rebel commanders and Russia aimed at stemming bloodshed that has threatened his ex-Soviet country's survival and ruptured East-West ties.