Yemen's besieged president defiantly rejected a proposal Saturday to leave office early and possibly end weeks of protests and bloodshed, while Oman's ruler pushed out three more top-level officials in attempts to quell widening demands for economic reforms and justice for the killing of a demonstrator.
In Libya, Moammar Gadhafi's forces drove out rebels near the capital, Tripoli, but opposition militias took control of a key oil port amid signs that the country could be staggering toward civil war with neither side able to mount a decisive offensive.
In other parts of the region, there were bursts of anger and warnings in anticipation of unrest.
Hundreds of Egyptians gathered outside Cairo offices of the nation's internal security services _ the main enforcers of Hosni Mubarak's former regime _ a day after protesters beat officials inside the agency's building in the Mediterranean port of Alexandria. In Saudi Arabia, authorities banned all forms of demonstration as calls grow for protest marches Friday in the Western-allied kingdom.
"The president should leave!" cried Redwan Massoud, a leader of the protesters at Sanaa University in Yemen as tens of thousands of demonstrators streamed through cities across the country in a show of resolve against President Ali Abdullah Saleh, who has been in power 32 years.
But Saleh _ a key U.S. ally in the campaign against al-Qaida _ dug in deeper. He rebuffed an offer by an opposition coalition to end the country's political crisis by stepping down by the end of the year. He instead stuck to his pledge to stay in office until elections in 2013 but not seek re-election.
He then suspended classes at the universities in the capital Sanaa and the southern port of Aden, which have been the centers for daily demonstrations inspired by the uprisings in Egypt and Tunisia. Dozens have already died in clashes, including four people killed during a Friday protest in the northern town of Harf Sofyan.
There are growing cracks in Saleh's regime in the Arab world's most impoverished nation. Several members of his ruling Congress Party resigned Saturday. But his swift rejection of the early exit proposal suggested he still believes he can ride out the revolt.
In neighboring Oman, meanwhile, Sultan Qaboos bin Said, who has led the nation for four decades, is tossing out more concessions to try to bring an end to a rare show of dissent. Protesters _ including oil workers in the south _ are pressing for more jobs and economic and political reforms. But unlike the other countries they have pledged their loyalty to the hereditary monarch.
The sultan replaced three top government positions Saturday _ just a week after dismissing six other Cabinet officials.
Oman's unrest remains small compared with Gulf neighbor Bahrain, but it is closely watched because of the country's strategic role as co-guardian of the Strait of Hormuz. Oman and Iran share authority over the crucial waterway at the mouth of the Gulf, which is the route for 40 percent of the world's oil tanker traffic.
Saturday's shake-up included the head of the Palace Office, which oversees security affairs, in an apparent attempt to ease calls to hold officials accountable for the killing of a protester last week. Also replaced was a minister who holds the most senior adviser post and another who deals with internal matters within the ruling structure.
The measures failed to halt sit-ins in the capital, Muscat, and the northern industrial city of Sohar, where the unrest began, but they were welcomed by many protesters.
"It was as if a black cloud has lifted. Long live the sultan, long live Oman," said Saeed Hamad, a protester outside the Sultanate's Shura council.
In Libya, Gadhaf's forces and rebel units continued their give-and-take battles.
Gadhafi loyalists moved back into the outskirts of Zawiya, just 30 miles (50 kilometers) west of Tripoli, with a surprise dawn attack under cover of mortar shells and later with an afternoon offensive. In the east, the pre-Gadhafi flag used by rebels flew over the key oil port of Ras Lanouf after the first major battlefield victory by forces trying to end Gadhafi's four-decade rule.
"We will fight them on the streets and will never give up so long as Gadhafi is still in power," said one of the rebels in Zawiya, who declined to be identified.
International pressure has been building for Gadhafi to step down. There have been no moves for military intervention, but Washington has not ruled out imposing a "no-fly" zone to protect rebel forces.
U.S. forces also were boosting their presence off the Libyan coast. Two Navy ships, the amphibious assault vessel USS Kearsarge and the amphibious transport dock USS Ponce, left an American base on the Greek island of Crete. Earlier this week, 400 Marines from the 2nd Marine Expeditionary Unit based at Camp Lejeune in North Carolina arrived in Crete.
The coming week includes calls for protest rallies in Kuwait on Tuesday and Saudi Arabia on Friday as the Arab groundswell for reform presses into new territory.
Saudi Arabia's Interior Ministry issued a statement outlawing all forms of demonstrations as contrary to Islamic laws and Saudi values. It warned that security forces were authorized to take action against violators.
The statement came a day after about 100 Saudi Shiites demonstrated after Friday prayers in the eastern region demanding the release of detainees and a Shiite cleric, Tawfiq al-Amer, arrested last week for calling for a constitutional monarchy.
Just over the causeway in Bahrain, thousands of Shiite protesters formed a huge human chain around the capital Manama as protests against the Sunni monarchy moved into its third week in the strategic country _ the host of the U.S. Navy's 5th Fleet. Organizers say some members of the Sunni minority joined Saturday's event.
Unlike the other pro-democracy movements, Algeria's demonstrations have yet to get off the ground.
On Saturday, police put down three separate march bids in the capital which also drew demonstrators who turned out in favor of President Abdelaziz Bouteflika.
A group that had been organizing the protests has split in two, with a political wing, which tried to march Saturday, and a grouping of human rights leaders and unions which has chosen to work more closely with the population.
Many Algerians say they are tired of conflict after being subjected to years of violence because of an Islamist insurgency.
Murphy reported from Dubai, United Arab Emirates. Associated Press writers contributing to this report: Maggie Michael in Tripoli, Libya; Paul Schemm in Ras Lanouf, Libya; Sarah El Deeb in Cairo, and Saeed El-Nahdy in Muscat, Oman.