SOFIA, March 28 (Xinhua) -- Bulgarian opposition on Wednesday wanted the country's Prime Minister Boyko Borissov to present the parliament information related to the massive expulsions of Russian diplomats by Britain and its allies.

"We are worried about the developing diplomatic crisis. We can call it a diplomatic war that resembles the Cold War period," Kristian Vigenin, secretary of the parliamentary group of the Bulgarian Socialist Party, told reporters.

Borissov had to come to the National Assembly and inform MPs about the situation, said Vigenin, who was a member of the European Parliament from 2007 to 2013, and Bulgaria's foreign minister from May 2013 to August 2014.

In particular, Borissov had to explain why on Tuesday he summoned Bulgaria's ambassador to Moscow for consultations, Vigenin said.

"To date, we have not seen convincing evidence, not to say any evidence that Russia was directly involved in the Scripal case," he said.

More than 20 Western countries have announced the expulsion of Russian diplomats, in response to the poisoning of a Russian ex-spy with a nerve agent.

Russia has denied any involvement in the poisoning of Sergei Skripal and his daughter Yulia at a shopping center in Salisbury, Britain, on March 4.

On Tuesday, the Bulgarian Government Information Service said in a statement that Borissov made a telephone conversation with Bulgarian Ambassador to the Russian Federation Boyko Kotsev.

"The two discussed the Scripal case, as well as the reactions to it in Russia, in the European Union, and within the international community," the statement said, adding that Borissov commissioned Kotsev to return to Sofia for consultations with the Bulgarian government.