Moscow, Apr 23 (IANS/RIA Novosti): Russia and the US are committed to boosting their efforts to jointly fight terrorism, Russian Foreign Minister Sergei Lavrov has said.

During a recent telephone conversation, Russian President Vladimir Putin and US President Barack Obama confirmed their commitment to strengthen security coordination, Lavrov said in response to a question about the Boston marathon bombings.

Lavrov declined to comment on reports that a Boston Marathon bombing suspect, Tamerlan Tsarnaev, had visited Russia.

"Sources in the US and Russian special services have already made the relevant comments on the issue and I have nothing to add," Lavrov said.

Earlier, ABC News said the second suspect, 19-year-old Dzhokhar Tsarnaev, was awake and has answered investigators' questions in writing from his hospital bed. He is still unable to talk after suffering throat and neck wounds, ABC said.

Three people were killed and 180 injured after two powerful explosions ripped through a crowd near the finish line of the Boston Marathon.

The other main suspect in the twin bomb attack, Tsarnaev's older brother Tamerlan Tsarnaev, 26, died of wounds sustained in a shoot-out with police.