Russia on Monday handed over to Poland copies of cockpit conversation recorders and other materials related to the investigation into the plane crash that killed Polish President Lech Kaczynski.

Polish Interior Minister Jerzy Miller thanked Russian investigators for their cooperation, but said Poland needed access to all documents related to the crash in order to conduct its own probe.

It was not immediately clear how much information remained to be handed over, but Russian officials said their probe was proceeding as quickly as possible.