A 17-year-old teenager and widow of a North Caucasus militant is suspected of being one of the suicide bombers who attacked the Moscow metro on Monday, BBC reports.

The teenager is identified as Dzhennet Abdurakhmanova from Dagestan, which like nearby Chechnya, is a breeding ground for militant violence.

Abdurakhmanova is believed to be the bomber who attacked the Lubyanka metro station on Monday, killing 20.

She is said to have had been married to a leading Islamist militant, Umalat Magomedov, who was killed by Russian security forces at the end of last year. A photograph of the young woman, published in the Russian newspaper Kommersant, bears a strong resemblance to a picture of the remains of one of the suicide bombers. On the picture Abdurakhmanova, wearing black, is seen with Magomedov, both holding guns.

Unnamed Federal Security Service (FSB) officials say Magomedov was an associate of Doku Umarov, the Chechen rebel leader claiming responsibility for Monday's metro attacks. Umarov, who calls himself the Emir of the Caucasus, said the attacks were an act of revenge for the killings of Chechen and Ingush civilians by the Russian security forces near the town of Arshty on February 11 and warned Russians to prepare for more blasts.

The second suspected bomber has not yet been identified, but is believed to have been the 20-year-old widow of a Chechnya militant, who was killed in 2009 for plotting the murder of the Chechnya President, Ramzan Kadirov. After her husband’s death, the woman, known as Marha Ustrahanova, had disappeared.

Meanwhile, the Bulgarian National Radio, BNR, citing France Press, reported Sunday that the dead toll from the Monday attack in Moscow has reached 40, after a man died overnight in the hospital. The injured are reported at 84; most of them still remain hospitalized and several are in critical condition.

On Thursday Russian President Dmitry Medvedev flew to Dagestan's capital Makhachkala to hold emergency talks with the leaders of Russia's troubled North Caucasus republics.

The visit came on the heels of an attack where 12 people, nine of them police officers, were killed in two suicide bombings in Kizlyar.