BEIRUT, April 30 (Xinhua) -- Lebanese Hezbollah leader Sayyed Hassan Nasrallah vowed Tuesday to defend the Syrian government, stressing the real friends of Syria would not allow it to fall.

In a televised speech, Nasrallah said his militia would particularly defend Lebanese Shiites living in the Al-Qusayr area of Syria.

"We won't leave the Lebanese in Qusayr's countryside vulnerable to attacks and we will not hesitate to help them ," he said, affirming Hezbollah's involvement in Syria's conflict.

Also, he said "extremist groups" operating near the Shiite shrine of Sayyida Zainab outside Damascus have threatened to destroy it, warning "if such a crime were to take place, it will carry with it grave consequences."

Hezbollah has come under criticism for reportedly fighting on the side of the Syrian government against rebels in the Al-Qusayr area and in Damascus suburbs.

Media reports in the past weeks said many Hezbollah members had been killed in fighting in Syria, but Nasrallah denied a large number of them had died in the conflict.

He also dismissed the recent Israeli and U.S. allegations that the Syrian forces had used chemical weapons in the battles, call them a "game" aimed at finding an excuse for foreign intervention in the unrest-torn country.