Russia said it would allow Polish investigators to examine the wreckage of a Polish plane that crashed in 2010, an incident that killed Poland’s then-President Lech Kaczynski and 95 other people.
In a statement, the Investigative Committee said it was granting access to the Polish officials at the end of May in response to a request from Warsaw.
The 2010 crash, which occurred near the Russian city of Smolensk, killed Kaczynski as well as his wife, the country's top military leadership, and other officials.
The group was traveling to attend ceremonies honoring Polish officers killed by Soviet secret police during World War II.
In 2011, an investigation by Poland’s government blamed the crash on errors by Polish pilots, poor guidance by Russian controllers in dense fog, and very poor visibility at the rudimentary military airport.
A separate report by Russian experts blamed the Polish crew and the alleged presence of a Polish Air Force commander in the cockpit.
In recent years, the crash has become a rancorous political issue in Poland, which has pit liberals against conservative supporters of Kaczynski, whose twin brother, Jaroslaw, now heads the ruling Law and Justice party.