Fighting in Yemen's south killed dozens of people Tuesday, as the violence and unrest that has engulfed the nation for months shows no signs of ending, despite the president's absence.

Government forces clashed with Islamist militants in the southern city of Zinjibar, more than a week after hundreds of militants seized control of the city. The defense ministry said Tuesday security forces had killed at least 30 militants, in what appears to be an increased effort to retake the area.

Fresh fighting also erupted in Yemen's second-largest city, Taiz. Witnesses heard explosions and gunfire as army tanks fired on gunmen. The violence in Taiz killed at least four people.

The fighting comes amid increased calls for Yemen's President Ali Abdullah Saleh to accept a peace deal put forward by the Gulf Cooperation Council that would end his nearly 33 years in power.

Mr. Saleh is currently receiving medical treatment in Saudi Arabia for wounds suffered during a rocket attack on his compound last week.

Diplomatic sources say Mr. Saleh sustained severe injuries, including burns to 40 percent of his body.

However, Yemen's acting leader, Vice President Abd al-Rab Mansur Hadi, has said Mr. Saleh is “making a strong recovery” and will return to the country within days. But there have been suggestions the Saudi government may block his return.

At the border between Saudi Arabia and Yemen, a man trying to cross into Yemen killed two Saudi border guards Tuesday. Saudi Arabia's Interior Ministry says the man trying to cross the border also was killed.

Clashes had diminished in Mr. Saleh's absence, although opposition tribesmen say government snipers in the Yemeni capital, Sana'a, have killed at least three supporters of tribal leader Sheikh Sadiq al-Ahmar.

On Sunday, Yemen's vice president ordered government forces to vacate opposition-controlled areas of the capital, while al-Ahmar began to evacuate his militia from government buildings and called for an end to the fighting.

Nearly 400 people have been killed since a popular uprising against Mr. Saleh began in January.