A group of Russian scientists have sounded the alarm over what they said were attempts by the head of the security service to openly justify Stalin's mass purges, the first such attempt in decades. In an open letter published by Kommersant broadsheet, more than 30 academics slammed Alexander Bortnikov, the head of the FSB security service -- the successor to the feared KGB -- for seeking to legitimise the mass purges known as the Great Terror.

Historians estimate about one million people perished in Stalin's purges in the 1930s out of around 20 million who died under his three-decade rule before his death in 1953. Since former KGB officer Vladimir Putin was first elected president in 2000, authorities have sought to promote a positive view of the Soviet past, including the role of Stalin, but Bortnikov's comments appear to mark a new step in this direction. In an interview with Russian government newspaper Rossiiskaya Gazeta published this week Bortnikov said the archives show that "a significant part" of the criminal cases of that period "had an objective side to them".