Damascus, Mar 22 (IANS/RIA Novosti): At least 42 people were killed, including a senior Muslim cleric, and over 80 wounded in an explosion at a mosque in downtown Damascus Thursday.

A suicide bomber set off an explosive device at the mosque during a religious lesson being given by Sheikh Mohammad Said Ramadan al-Buti, a top Sunni Muslim preacher and long time supporter of Syrian President Bashar al-Assad, state-news agency SANA reported Thursday.

The 84-year-old cleric and religious scholar was killed in the blast. Sheikh al-Buti used to deliver mosque sermons Fridays on state television. He particularly condemned terrorism and violence.

Al Arabiya reported that the Free Syrian Army, fighting the regime of Assad, denied any involvement in the death of Sheikh al-Buti.

"We in the Free Syrian Army do not take any responsibility for this operation. We do not do these types of suicide bombings and we do not target mosques," reported Al Arabiya citing rebel spokesperson Loay Maqdad.