Russia has warned that it could block international flights through its airspace if the EU goes ahead with new sanctions over the Ukraine conflict.
The EU is expected to announce shortly whether further sanctions will take effect now or be put on hold.
The EU has said this will depend on how the situation develops on the ground.
Pro-Russian separatists have recently made big gains, but a fragile ceasefire in eastern Ukraine appears to be holding despite some sporadic shooting.
Fighting in the east has killed some 2,600 people since April. The truce and roadmap to peace were agreed on Friday.
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.
Russian Prime Minister Dmitry Medvedev warned that Moscow would respond “asymmetrically” to further sanctions.
A Russian airspace ban “could drive many struggling airlines into bankruptcy”, he told a Russian daily.
“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.
“We work on the basis of friendly relations with our partners, and that’s why Russia’s skies are open to flights. But if we are restricted then we’ll have to respond,” he told Vedomosti (in Russian).
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.
Last week an EU official told the BBC that further sanctions would deepen the existing measures, affecting Russia’s access to capital markets, dual-use goods which can be used for military purposes, defence equipment and some other sensitive technologies.
Richard Galpin in Donetsk: “We’ve heard the sound of quite a number of mortars being fired”
They would also expand the visa bans and asset freezes on Russian officials and entities, including separatist leaders in Ukraine.
The Ukrainian authorities in Donetsk region say President Petro Poroshenko is expected to visit Mariupol on Monday.
It is the last city in Donetsk region still held by the Ukrainian government and some shelling was reported there at the weekend. It is a strategic port on the route to Crimea, the peninsula annexed by Russia in March.
There was also some fresh shelling near Donetsk airport. The rebels are still holding the city, and have pushed back Ukrainian forces on the outskirts.
On Sunday, Ukrainian security official Volodymyr Poliovyi said 864 Ukrainian soldiers had been killed since the conflict began.
So far there have been no big prisoner exchanges since the ceasefire took effect.
12-point peace roadmap – key elements
- Ensure an immediate bilateral ceasefire
- Carry out decentralisation of power, allowing temporary local self-government in areas of Donetsk and Luhansk in eastern Ukraine under a “special status” law
- Immediately free all hostages and illegally detained persons
- Ensure monitoring on the Ukrainian-Russian border and a security zone
- Ensure the holding of snap local elections in Donetsk and Luhansk
- Remove illegal armed groups, military hardware, and all fighters and mercenaries from Ukrainian territory
- Pass a law against the prosecution and punishment of people over certain events in Donetsk and Luhansk region
Posted by the OSCE on its website (in Russian).