A rift was growing between Britain and key allies yesterday as European diplomats pushed back on calls for a firmer response to Russia's weekend naval clash with Ukraine. The fracture in the Western alliance sets the stage for tense exchanges when European, US, and Russian leaders meet at a G20 summit in Argentina later this week.

Britain, Poland, and the Baltic States have urged other members of the EU 28 to impose extra measures when existing sanctions against Russia are renewed in December.

The calls have been backed by the US, which on Tuesday called on European countries to tighten sanctions and re-think Nord Stream-2, an undersea gas pipeline linking Russia with Germany.

France and Germany, which brokered a ceasefire and tentative peace accord between Vladimir Putin, the Russian president, and Petro Poroshenko, the leader of Ukraine, in 2015, are understood to fear such a move could split the bloc and further inflame tensions.

EU countries including Italy, Greece, Bulgaria and Cyprus have argued for a softer stance on Russia and have expressed skepticism about the utility of the sanctions regime.

Britain was among a group of member states who in recent days have pushed for mention of further restrictive measures against Russia, an EU diplomatic source told The Daily Telegraph.