BBC: Key Yemeni General Ali Mohsen al-Ahmar, who is close to President Ali Abdullah Saleh, says he has joined the protest movement against the regime.
Two other army commanders are also reported to have resigned.
The announcement comes a day after the president dismissed his entire cabinet in apparent response to the protests against his rule. He asked them to stay in place in a caretaker capacity.
Meanwhile in the north, 20 people have been killed in fighting, reports say.
Fighting between Shia rebels, Yemeni troops and their tribal allies erupted over a north Yemen military site at the entrance to the northern province of al-Jawf, military and tribal sources are quoted as saying by the AFP news agency.
'Preserving stability'
Gen Mohsen is the commanding officer of a division of the army which has sent units to a main square in the capital, Sanaa, where protests have taken place.
"The crisis is getting more complicated and it's pushing the country towards violence and civil war," the general - who commands an armoured infantry division - said in a statement broadcast by al-Jazeera television.
"According to what I'm feeling, and according to the feelings of my partner commanders and soldiers... I announce our support and our peaceful backing to the youth revolution... We are going to fulfil our duties in preserving security and stability."
A BBC correspondent says that one by one, the pillars of President Saleh's power are being knocked away. » | Monday, March 21, 2011
