KIEV government forces claimed today that they had retaken the airport in the Ukrainian city of Donetsk after fierce fighting.

Pro-Russian fighters said that the battle for the Sergei Prokofiev airport had left more than 50 of their comrades dead.

The Donetsk airport was under full government control by late morning, Ukraine’s acting Interior Minister Arsen Avakov said, adding that dozens of insurgents may have been killed in the fighting but government forces did not suffer any casualties.

Ukrainian fighter jets and helicopter gunships had unleashed air strikes on the fighters who had taken control of the terminal.

Members of the public were urged to stay indoors following reports that the fighting had spread to residential areas of the city.

Unidentified men stormed Donetsk’s main ice hockey arena and set it ablaze, according to the mayor’s office.

And heavy machine-gun fire could still be heard yesterday morning amid signs of continuing resistance.

Fighting was also reported in Mariupol, Biryukovo and Sloviansk, with further rebel losses claimed.

Donetsk People’s Republic prime minister Alexander Borodai said: “We have lost more than 50 volunteers.”

In the neighbouring Lugansk region, which like Donetsk has declared independence from the government, the Ukrainian Border Guards Service claimed that its officers fought with a group of gunmen trying to break through the border from Russia.

It said one intruder was wounded and the border guards seized several vehicles loaded with Kalashnikov assault rifles, rocket grenade launchers and explosives.

The interim government in Kiev has threatened activists that it will press ahead with the operation until they are killed.

Speaking at a televised government session on yesterday, Deputy Prime Minister Vitaly Yarema said the “anti-terrorist operation” will go on “until all the militants are annihilated.”

In Moscow, Russian Foreign Minister Sergey Lavrov voiced a strong concern about the interim authorities’ decision to intensify the military operation in the east and called for an immediate end to fighting.

Russia has kept up pressure for Ukraine to decentralise its government, which would give more power to the regions, including those in the east.