Russian Foreign Minister Sergei Lavrov on Saturday called for an OSCE investigation into who was behind the deaths of dozens of people in Kiev last month in attacks by snipers, saying the truth could no longer be "covered up".

Lavrov's comments came after Estonia's top diplomat told EU foreign policy chief Catherine Ashton in a phone call leaked this weak that the then-Ukrainian opposition to president Viktor Yanukovych may have been involved in the attacks.

"The latest information about the so-called snipers case can no longer be covered up," Lavrov told a news conference in Moscow with his Tajik counterpart.

"We have proposed that the OSCE (Organisation for Security and Cooperation in Europe) takes up an objective investigation of this and we will ensure there is justice.

"There have been too many lies, and this lie has been used too long to push European public opinion in the wrong direction, contrary to the objective facts."

Western states have blamed Yanukovych's now disbanded elite riot police force for much of the killing that rocked in Kiev in February.

However Russia has strongly emphasised the leaked phone call between Estonian Foreign Minister Urmas Paet and Ashton as evidence for its argument that the new post-Yanukovych government in Kiev is made up of dangerous extremists.

Lavrov's call for a full probe indicates that this is an issue Russia will not allow to drop, risking new tensions with the West.

In the audio of the February 26 call, whose authenticity was confirmed by Estonia, Paet told Ashton he was informed in Kiev that "they were the same snipers killing people from both sides."

Dozens of protesters and around 15 police officers were killed in the attacks.

Paet, who had held talks with Ukraine's new leaders on February 25, added: "It's really disturbing that now the new coalition, they don't want to investigate what exactly happened."