"We have been blockaded for over a month and have not received reinforcements, equipment, or even a drop of water in over two weeks," an officer at the embattled base said by telephone.
The latest clashes near a local football stadium left at least a dozen people injured. The clashes in Zinjibar have forced thousands of families to flee to the southern city of Aden.
In the central city of Taiz on Saturday, tribesmen shot dead four Republican Guards and wounded eight others. The fighting between the guards and the tribesmen ended Sunday morning, witnesses said.
Reuters news agency quoted a Yemeni Cabinet official in Riyadh on Sunday as saying President Ali Abdullah Saleh will not cede power until he returns to oversee a transition.
Yemen has been paralyzed by six months of mass protests against Saleh's three-decade rule. After surviving an assassination attempt last month, Saleh went to Saudi Arabia for treatment.
The Cabinet official visiting the president on Sunday told Reuters Saleh planned to support a Gulf transition plan that has already collapsed three times when the president backed out of signing at the last minute.
"Saleh plans to support the Gulf Cooperation Council deal and he asked the foreign minister to do everything to make the plan succeed," said the official, who asked not to be further identified. "But in order for the power to be transitioned, the president has to be in Yemen."
He also said Saleh expected to manage the transition himself: "To have a proper election you would need six to eight months and during that period Saleh will still be president."
Opposition groups and the hundreds of thousands protesting across Yemen want an immediate change in government, which Vice President Abd-Rabbu Mansour Hadi has run in Saleh's absence.
"Saleh's return has become impossible and if his health improved, which I doubt, we say to him, stay where you are and take the rest of your family with you," said Samia Al-Aghbari, a prominent activist in Taiz. "They want to burn this country to the ground."
Despite the defection of several military leaders and hundreds of troops, Saleh's son remains in control of the powerful Republican Guard that protesters in Taiz say tried to attack their camp Saturday night.
