Russia does not consider the international inquiry into the crash of a Malaysian Boeing in Ukraine to be objective because it has been barred from it, Russian presidential press secretary Dmitry Peskov said.

"As you're aware, our attitude toward the current investigation and the court in the Netherlands is well-known: we do not consider this investigation to be objective," Peskov told journalists on Wednesday.

Russia has offered its participation and cooperation to identify those responsible from the very beginning, he said.

"Such a possibility was denied to Russia, so we cannot recognize the results of such an investigation without our involvement as being objective," Peskov said.

Asked to comment on a victims' families' letter to the Russian authorities, which was published in the newspaper Novaya Gazeta, Peskov said he was unaware of the letter and declined to comment.