The Moscow subway explosion that killed 41 people earlier this month was caused by a suicide bomber, Russia's security service confirmed Tuesday.

The bomb that tore through a crowded Moscow subway at rush hour on Feb. 6 was made of ammonia saltpeter and aluminum powder, the ITAR-Tass and Interfax news agencies reported, citing the Russian Federal Security Service's press office.

The composition of the Moscow subway bomb was identical to one used on a commuter train in the southern Russian city of Yessentuki in December, the security service said.

The December suicide bombing, which occurred two days before elections to Russia's State Duma, ripped through a commuter train near Yessentuki in Russia's southern Stavropol region, killing 47 people aboard.

Security service officials had already said there was a connection between the two blasts.

At the time of the Moscow subway blast, Russian President Vladimir Putin blamed it on Chechen rebels.

More than 100 people were also wounded in the explosion, which had an equivalent force of nearly five kilograms of TNT.