Russian prime minister Dmitry Medvedev has warned the country could close airspace to international flights of the European Union goes ahead with further sanctions over the conflict in Ukraine.

The EU will announce shortly whether further sanctions will take effect now or be put on hold, with sanctions largely depending on developments on the ground.

Pro-Russian separatists in eastern Ukraine have recently made big gains, but a fragile ceasefire in the area appears to be holding after beginning on Friday.

Medvedev warned that Moscow would respond “asymmetrically” to further sanctions.

“If there are sanctions related to the energy sector, or further restrictions on Russia’s financial sector, we will have to respond asymmetrically. For example, restrictions in the transport sector,” said Medvedev.

“We work on the basis of friendly relations with our partners, and that is why Russia’s skies are open to flights. But if we are restricted then we’ll have to respond,” he told Vedomosti in an interview.

Airlines would have to pay far more for fuel if Russia blocked their routes to Asian destinations, and flight times would be longer in many cases.

Russia has repeatedly denied accusations by Ukraine and the West that it has been sending troops into Donetsk and Luhansk regions to help the rebels, who want to establish an independent state.