European governments are to push for tighter sanctions against the Kremlin and against Russian separatists in eastern Ukraine on Thursday.

But the new leftwing Greek government of Alexis Tsipras is likely to use the emergency meeting of foreign ministers in Brussels to pick its first fight with the rest of Europe.

The meeting was called at short notice by Federica Mogherini, the EU’s foreign policy coordinator, who has been forced to back down from a position calling for a relaxation of pressure on Moscow, as a result of last week’s shelling by separatists of the town of Mariupol that killed 30 civilians.

In an unusual statement on Tuesday released in the name of all 28 EU heads of government, Donald Tusk, the president of the European council, who chairs EU summits, held Moscow responsible for the shelling and told the foreign ministers to draw up additional sanctions options to be put to a summit of leaders in two weeks.

Britain, Poland and Lithuania are to push at Thursday’s meeting for a ratcheting up of the pressure on President Vladimir Putin, favouring stiffer and broader economic sanctions against Russia.

Decisions already drafted for Thursday’s meeting say the foreign ministers are to carry out “further preparatory work on further restrictive measures” before presenting the options to the summit on 12 February.

But the UK-led push for broader punishment of Russia, whose economy has nosedived as a result of existing sanctions and the collapse in the price of oil, will face ample opposition.

The meeting may result in lesser action, such as the blacklisting of separatist leaders in eastern Ukraine who have been involved in the current escalation of violence.

The draft statement says the EU “agrees to extend restrictive measures targeting persons and entities for threatening or undermining Ukraine’s sovereignty and territorial integrity” and says a new blacklist should be drafted within a week.

Between March and July, EU leaders have to decide whether to extend the sanctions imposed over the past year. The escalation of violence makes it unlikely that the penalties against Russia will be eased.

Senior government officials from EU member states say the violence in eastern Ukraine is at the worst levels seen since last summer and are at a loss to explain Putin’s aims, except to keep Ukraine as weak and unstable as he can.

But there is plenty of resistance to the sanctions from Hungary, Cyprus, Slovakia and the Czech Republic.

The triumph of Tsipras in Greece on Sunday complicates the situation, since summit decisions on sanctions are carried by consensus and the new Greek prime minister has a veto.

Tsipras and his colleagues have a track record of supporting Russia and have denounced EU policy on Ukraine, as well as the policies of Nato and the US.

The Greeks complained bitterly on Tuesday that they were not consulted on the statement blaming Russia for Mariupol and calling for stiffer sanctions. This was untrue. Mogherini spoke to Tsipras by telephone.

Before coming to office on Sunday, Tsipras’s Syriza movement was a regular critic of the EU sanctions against Russia.

The unusual statement prepared by Tusk on Tuesday said all EU heads of state and government “condemn the killing of civilians during the indiscriminate shelling of the Ukrainian city of Mariupol on 24 January 2015 … We note evidence of continued and growing support given to the separatists by Russia, which underlines Russia’s responsibility.”

“Greece does not consent to this statement,” the Tsipras government promptly declared. “It was released without the prescribed procedure to obtain consent by the member states and particularly without ensuring the consent of Greece.”

The row suggests that Tsipras, making his EU summit debut in Brussels in two weeks, could use his first appearance to block an EU consensus.

The German chancellor, Angela Merkel, is the west’s key interlocutor with Putin and has led the diplomatic push for a settlement while taking an increasingly hard line against Moscow.

She spoke by phone to Barack Obama on Tuesday about Ukraine and they both agreed Moscow should be held responsible for the Mariupol attack.

Merkel is also the central figure in Tsipras’s campaign to get the EU to reduce Greece’s staggering debt burden and ease imposed austerity measures.

A Tsipras veto over Russia sanctions in defiance of Merkel would be the worst possible start in his efforts to get the EU to cut Greece some slack.