Russian Prime Minister Vladimir Putin urged on Tuesday law enforcement and security agencies to find masterminds and accomplices of the deadly twin Moscow blasts, saying it as a matter of honor.

Those responsible for the tragic explosions that claimed at least 39 lives should be "scraped out from the bottom of the sewers," said Putin as quoted by news agencies.

"We know they (the masterminds and accomplices) have lain in hiding, but it is a matter of honor for law enforcement agencies to bring them out from the sewer into God's light," said Putin at a transport security meeting.

"I am sure this will be done," he added.

Two deadly blasts struck the Lubyanka and Cultural Park subway stations in central Moscow during rush hours on Monday morning, with an interval of around 45 minutes, killing at least 39 people and injuring more than 70.

Ensuing the blasts, Russian President Dmitry Medvedev on Tuesday proposed to prevent terrorism by improving legislation.

Both Medvedev and Putin have pledged to fight terrorism to the end without hesitation on Monday.

The blasts were confirmed as having been set off by two female suicide bombers who probably were linked to terrorist groups in North Caucasus.

Moscow held a Day of Mourning Tuesday for victims of the catastrophe with flowers, candles and voluntary memorials at the two metro stations.

Flags were flown at half mast over Kremlin and the State Duma buildings, and entertainment programs were suspended in some TV channels and theaters.

Monday's bomb attacks were the deadliest in the capital city of Russia since 2004.