Sanaa/Aden: More than 300 members of Yemen's security forces have defected, opposition sources said on Wednesday, which could bolster opponents demanding that President Ali Abdullah Saleh end his 33 years in power.

The defections come amid intensified military attacks by the Yemeni air force and ground troops on what the government says are Islamist militants affiliated with Al Qaida in south Yemen.

Yemen has been shaken by months of protests against Saleh's three-decade rule, a resurgent Al Qaida and a separatist rebellion in the south.

"From the podium of the Square of Change in Sana'a, an announcement has been issued that 150 soldiers from the Republican Guards, 130 Central Security soldiers and 60 policemen have joined the rebellion," an opposition message said.

The defections also included 150 members of the Republican Guards led by Saleh's son, Brigadier General Ahmad.

If confirmed, the mutinies would represent a major blow to Saleh, who has spent the past three weeks receiving medical treatment in Saudi Arabia after he was injured in an attack on his palace on June 3.

The defections are the latest in a series by security forces since an uprising against Saleh's rule began in February. Most prominent was the defection in March of Brigadier General Ali Mohsen, who has since sent in his troops to guard protesters in Sana'a.

The protests have culminated in gunbattles between Saleh loyalists and gunmen from the powerful Hashed tribal federation in Sana'a that brought the country to the verge of civil war.

Yemen has been largely quiet with a ceasefire in place since Saleh was injured in the attack, which investigators say was caused by explosives planted in the palace mosque where he and several senior government officials were praying

Saleh, 69, who has not been seen in public since the attack, has resisted pressure from the United States and Saudi Arabia to hand over power to his deputy, Abd Rabbu Mansour Hadi, under a Gulf nations' initiative to end the crisis.