SANAA, Yemen -- Several top figures who defected from the embattled Yemeni president's camp set up their own opposition party Monday in another blow to the long-time ruler who has clung to power despite near-daily protests demanding his ouster and defections by key allies.

Meanwhile, police in a southern port town fired tear gas and live ammunition at thousands of protesters calling for President Ali Abdullah Saleh to step down, injuring 45 people.

The developments underscore Yemen's precarious situation after two months of mass protests over the lack of freedoms and extreme poverty. The country's opposition, inspired by the uprisings in Egypt and Tunisia, says nothing short of Saleh's immediate departure would end the unrest.

Yemeni rights groups say the crackdown has killed more than 120 people, but it has not deterred crowds from gathering.

According to activist Riyadh al-Absi, of the 45 protesters hurt in Monday's violence in the Red Sea port of al-Hudaydah, 12 were wounded by bullets fired by plainclothes policemen. Police used batons to beat protesters who responded by throwing stones, al-Absi said.

In the capital Sanaa, several top figures and lawmakers -- many of them defectors from Saleh's ruling Congress Party -- set up their own bloc, entitled "Justice and Construction Bloc" and issued a statement insisting that Saleh relinquish power.

U.S.-educated Mohammed Abulahoum, who is also a leader of the powerful Bakeel tribe, the second-largest tribe in Yemen, was among the founding members. Khaled al-Wazeer, who was transport minister before he defected, was also among the party's founders.

Several women were among them too, including Huda al-Ban, who resigned last month as human rights minister. The group said it would strive to "establish a civil society based on democracy, peaceful transfer of power and respect of others."

Saleh's camp has been hit by a wave of defections and resignations since late March when security forces shot dead more than 40 demonstrators during a protest in Sanaa. The defectors have also included key allies in the military, powerful tribes, ambassadors, provincial governors and some managers of the state-run media.

As part of efforts to resolve Yemen's turmoil, representatives from the opposition held talks in the Saudi capital Sunday with the foreign ministers of the six-nation Gulf Cooperation Council to discuss the GCC proposal under which Saleh would transfer power to his deputy.

The GCC proposal also offers the president immunity from prosecution, which the opposition has rejected.

A statement issued Sunday night by the ministers said they will meet Yemen government representatives after they heard the opposition views. No date for that meeting has been set.

"The opposition representatives have confirmed their wish to end the current crisis to save the blood and the interests of the Yemeni people," the statement said.

Security forces opened fire on protesters in the capital on Sunday as marchers neared the office of the special forces, headed by Saleh's son. Witnesses said the forces fired live ammunition, and used tear gas and water cannons to disperse the crowd. Security agents chased protesters in side streets, and the protesters said at least 220 people were wounded, including 20 people hit by gunfire.

The official SABA news agency said 14 policemen were injured by stones in Sunday's evening protests in Sanaa.