Ukrainian government forces are defending the approaches to Mariupol, a key port city. Photo: AFP

A statement said the ministers, who will meet on Thursday, should "consider any appropriate action, in particular on further restrictive measures".

It urged Russia to observe last September's Minsk ceasefire deal, which has been ignored amid clashes between Ukraine's army and pro-Russian rebels.

More heavy shelling has been reported.

The Ukrainian military said nine of its soldiers had been killed in the past 24 hours as fighting raged at several points in eastern Ukraine.

The military, quoted by Ukraine's Unian news agency, said there had been heavy rebel mortar and artillery fire near the town of Debaltseve and the village of Luhanskaya.

More than 5,000 people have been killed in fighting since the rebels seized swathes of the Donetsk and Luhansk regions last April, according to UN estimates. More than a million people have been displaced.

EU foreign ministers decided to hold an extraordinary meeting on Thursday after rockets were fired at the weekend on the outskirts of Mariupol, a key port city held by Ukrainian government forces. Kiev accused the rebels of killing 30 civilians in the attack.

Under EU procedures, the ministers could ask the European Commission to draw up further sanctions, which would then go before the EU heads of state and government for approval. An EU summit is scheduled for 12 February.

Nato Secretary General Jens Stoltenberg has urged Russia to stop providing military support to the rebels.

Nato and Kiev accuse Moscow of regularly sending troops and heavy weapons to help the rebels - something it has repeatedly denied.

Ukraine: the human cost

• Some 5.2 million people live in conflict-affected areas and 1.4 million are considered "highly vulnerable and in need of assistance"
• More than a million people have fled their homes, with 633,523 living as displaced persons within Ukraine and 593,622 living outside Ukraine, mostly in Russia
• More than 5,000 people have been killed in the fighting and more than 10,300 injured

Sources: UN report of 9 January for refugee figures; news reports for casualty estimates