Bulgaria said it recalled its ambassador from Russia on Tuesday to discuss the nerve agent attack in Britain which London blames on Moscow.

The announcement marked a toughening in the former communist country’s position, four days after Prime Minister Boyko Borissov had said he had no plans to recall the envoy, as reported by www.usnews.com.

Bulgaria, which holds the rotating EU presidency, has not gone as far as Britain and other countries in the bloc which have directly accused Russia of carrying out the attack and have expelled Russian diplomats.

Borissov had said on Friday that while there was “high probability” that Russia was behind the attack, he needed more hard evidence and was worried that the recall of EU ambassadors would further damage relations with Russia.

Borissov and Bulgaria’s ambassador in Moscow, Boyko Kotsev, had discussed the attack on former Russian double agent Sergei Skripal and his daughter, as well as reactions in Russia, the EU and the international community, the government’s press office said.

Britain accuses Moscow of using the Soviet-era military-grade nerve agent Novichok in the attack in the cathedral city of Salisbury, a charge which Russia has denied.