Pro-Russian insurgents driven out of their key stronghold in eastern Ukraine have converged on the city of Donetsk to renew their fight against the Ukrainian government.

Ukrainian troops yesterday forced the rebels out of Slovyansk, a city of about 100,000 that had been the centre of the fighting. That success suggests that the government may finally be making gains in the months-long battle against the insurgency.

It was not yet clear, however, whether the capture of Slovyansk has permanently crippled the rebels.

Rebel fighters from Slovyansk and other towns taken over by the Ukrainian army were today milling around central Donetsk, where the separatists have declared independence in the name of the Donetsk People's Republic.

The insurgents control the regional administration building and move freely about the city centre, but an attempt in late May to take control of the Donetsk airport was repelled by Ukrainian forces after a furious battle that left dozens of rebel fighters dead.

Igor Girkin, the defence minister of the separatist republic, said in an interview with the Russian television channel Life News that he had arrived in Donetsk from Slovyansk.

Pro-Russian insurgents also have been fighting Ukrainian troops in the neighboring Luhansk region, which like Donetsk sits along the border with Russia.