MOSCOW, Aug 31: Ten people were killed and 51 injured on Thursday in an explosion outside a Moscow subway station shortly after rush hour, a spokesman for Russia's FSB security service said.

Of the injured, 49 were hospitalized and two were treated at the scene, said the spokesman, Sergei Ignatchenko. The Moscow mayor, Yury Luzhkov, blamed the blast on an act of terrorism, but other officials said they were looking into all leads.

"With a great deal of probability it can be said we are talking about a premeditated explosion carried out by a terrorist female suicide bomber," an interior ministry official told journalists earlier.

The explosion caused carnage outside the station and came just a week after 90 people were killed in twin plane crashes classified by Russian officials as "terrorist acts."

An Islamist group calling itself the Islambouli Brigades claimed responsibility for a blast outside a Moscow subway station which killed at least 10 people on Tuesday, in a statement posted on an Islamist website.

The group initially denied a claim of responsibility attributed to it on an internet site, but then issued a statement saying it had carried out "this heroic operation in support of Chechen Muslims." -AFP