Russian investigators have identified the second suicide bomber who took part in the Moscow metro bombings last week as Mariam Sharipova, a 28-year-old Dagestani.

The Investigative Committee of the Prosecutor-General's Office said that Sharipova had set off an explosive device at the Lubyanka metro station on March 29.

Tuesday's announcement was issued four days after officials confirmed Dzhanet Abdullayeva as the other attacker in the double suicide bombing.

Abdullayeva, 17, was also from Dagestan and the widow of a fighter who officials said had been killed by security forces on December 31.

The morning rush-hour attacks on the Lubyanka and Park Kultury metro stations, around 40 minutes apart, left 40 people dead and more than 80 injured.

Father's identification

A spokesman for the FSB security service told the AFP news agency that Sharipova was the wife of Magomedali Vagapov, a fighter in the North Caucaus whose whereabouts are unknown, but who is believed to be alive and active.

On Friday, Rasul Magomedov told the Novaya Gazeta, a Russian newspaper, that Sharipova was his daughter.

"My wife and I immediately recognised our daughter" after photographs of the severed heads of the two suicide bombers were published in Russian media, Magomedov told the paper.

Magomedov told Novaya Gazeta that Sharipova graduated with honours from a local university in 2005 and since 2006 had taught computer science in Dagestan.

He told Komsomolskaya Pravda, another Russian newspaper, that his family, including Sharipova's two brothers, had been under pressure from the authorities for the past several years.

His elder son, Anvar, was once found abandoned in the woods after having been tortured for hours after he was detained by police, Magomedov told the paper.

Magomedov's younger son, Ilyas, was detained in a special operation and given a nine-month jail sentence, Komsomolskaya Pravda said.

The "Emirate of the Caucasus", which is fighting to impose a state based on sharia law in Russia's North Caucasus region, has claimed responsibility for the metro attacks.