Yemeni President Ali Abdullah Saleh Monday appointed Major General Ahmed Saeed bin Brik as the new commander of the Eastern Military Area and the Brigade 27 Mika, to replace Major General Mohamed Ali Mohsen, who declared he was joining in protest movements, the Defence Ministry said.

Saleh, who has been facing weeks-long youth-led street protests demanding an immediate end to his 33-year rule, also appointed Colonel Hussein Mshaba as the commander of 15 Infantry Brigade in the northern troubled province of Amran to replace another defected commander.

Saleh's decision came days after both former commanders defected from the government to join the opposition-led demonstration in protest against March 18 shootings that killed 52 protesters outside Sanaa University in the capital.

The two commanders announced defection together with President Saleh's half brother, Major General Ali Mohsen al-Ahmar, the commander of the Northwest Military Area, also known as 1st Armored Division, to join the protesters.

Al-Ahmar also vowed in a video-tape statement to protect the protesters and demand Saleh to immediately step down in order to avoid the country further bloodshed.

The March 18 shooting and al-Ahmar's defection drew more support from senior government officials, diplomats, security and army officers for anti-Saleh protests.

The official Saba news agency on Sunday quoted Saleh as saying that "if a military mutiny takes place, then a war would be launched in order to regain control over the country."

Saleh admitted that he has already lost control over five provinces, which were led by defected commanders while al-Qaida militants seized four towns and a weapon factory in southern provinces of Abyan and Shabwa.

Meanwhile, a provincial tribal chieftain told Xinhua on Monday that dozens of Muslim extremist militants have been surrounding a camp of the Republican Guards in the district of Arhab, some 30 km north of the capital of Sanaa. ( A senior official of the Interior Ministry told Xinhua on condition of anonymity that authorities are preparing to launch air raids against those militants in Arhab.