French foreign minister, Laurent Fabius, said on Wednesday that Russia would face more EU sanctions if pro-Russian separatists attack the Ukrainian port city of Mariupol.
Fabius told France Info radio: "We made it clear to the Russians that if separatists attack Mariupol, things would be drastically altered, including in terms of sanctions," Fabius said.
Pro-Russian separatists took control of the key railway hub of Debaltseve on Feb. 18 after days of fierce fighting and have been moving to take over the Ukrainian port city of Mariupol since Friday.
"At a European level the question of sanctions would be raised again," Fabius added.
Fabius's comment comes one day after French, German, Ukrainian and Russian foreign ministers called for the heavy weapons to be withdrawn by both sides, and for the Organization of Security and Co-operation in Europe monitoring mission in eastern Ukraine to be reinforced.
A cease-fire was signed between Ukrainian forces and pro-Russian separatists in Minsk on Feb. 12.
The cease-fire agreement includes the withdrawal of heavy weaponry from combat areas, the withdrawal of all foreign-armed formations and the release of all hostages and unlawfully detained persons.
The OSCE said last week that it had not seen either side complying with the truce.