Chechen fighters have taken the responsibility for the destructive explosion in the Russian Sayano-Shushenskaya hydro-electric power plant that happened earlier this week.

In a letter the terrorists said in a letter posted on a rebel website that they had used an anti-tank grenade for the explosion which thought to have killed over 70 people, BGNES reported.

"Glory to Allah, on August 17 through our efforts, a subversive operation was carried out in Khakasia at the Sayano-Shushenskaya hydro-electric dam", the letter from a group calling itself the Martyrs' Battalion said.

"In the machine hall we managed to plant an anti-tank grenade with a timer, the blast of which caused much stronger damage than we could have hoped for", the letter, which was published on the www.kavkazcenter.com website, said.

Three of the plant's 10 turbines were reportedly destroyed and three others damaged.

It would cost Russia at least USD 1,2 B to rebuild the turbine room. Repairs are estimated to take from two to five years. In the meantime the plant would produce no electric power for Russian industry.