Russia called for international probe into factors responsible for the Ukraine crisis, a parliament speaker said Tuesday.

"Only unbiased legal evaluation of facts...will show the truth," Sergei Naryshkin, speaker of the Russian State Duma, or the lower house of parliament, told a round table discussion over European politics.

Naryshkin particularly mentioned the Council of Europe (CoE) as the organization that should be responsible for the investigation, saying Europe is now suffering from a crisis of trust primarily caused by the deadly confrontation in Ukraine.

However, "far from all significant legal facts of the Ukrainian crisis" had been so far reflected in the assessments of Venice Commission, the CoE's advisory body focusing on democracy and human rights issues, Tass news agency quoted Naryshkin as saying.

In the past seven months, the unrest involving the rebels and Ukrainian forces in east Ukraine has killed more than 4,000 people, according to the United Nations.

The speaker also suggested that the Parliamentary Assembly of the Council of Europe (PACE) needs "a profound reform of its regulatory procedures and other substantive aspects."

In April, the PACE barred Russian delegates from joining the assembly's observer missions and deprived their voting rights in the body after Russia took Crimea from Ukraine.