SANAA, Yemen - Security forces and government loyalists struck protest camps across Yemen on Thursday, hurling rocks, beating protesters with sticks and firing rubber and live bullets, hoping to break the will of thousands camped in squares for over a month, demanding their longtime authoritarian leader leave power.

The violence underscored the chipping-at-the-edges tactic of President Ali Abdullah Saleh, who has ruled Yemen for over 30 years. He does not appear to have the will -- or perhaps the capabilities -- to disperse the demonstrators conclusively. In the past few weeks, he has unleashed fiery assaults on protesters in different cities using a mix of security forces and paid thugs, apparently hoping to wear them out.

It is just one of the problems this extremely poor, tribal country faces. Even before protests began in mid-February, Yemen's government was struggling to confront one of the world's most active al Qaeda branches, a secessionist rebellion in the south and a Shiite uprising in the north.

Saleh is a key ally in the U.S. campaign against the al Qaeda terror network.

On Thursday, al Qaeda militants ambushed police as they ate lunch at a checkpoint. In a gunfight, three militants and three police were killed, said a security official in the province of Marib.

In the southern province of Taiz, police hurled canisters of choking gas to break up a rally of several thousand. Government loyalists joined in, attacking protesters with iron rods, sticks and knives, witnesses said.

"Thugs -- security forces in plain clothes -- attacked us," said demonstrator Bushra al-Maqtari.

Several hours later, police and paid thugs rushed at the demonstrators again, adding rubber bullets and live fire to violently disperse the crowd. Medics said some 80 protesters were injured, at least four with gunshot wounds.

A similar attack took place against protesters camped in the Yemeni capital.

Mohammed al-Abahi, a doctor in charge of a makeshift hospital at the encampment, said eight people were injured in the attack. He said two were shot, while others had breathing difficulties from tear gas fired by police who tried to separate the two groups.

Following the attacks by thugs and security forces, demonstrators rushed to gather in the public squares again. Men wrapped bandannas around their heads with the red-white-and-black colors of the Yemeni flag stood shoulder-to-shoulder in some areas. Others wrote on their foreheads in markers: "Leave."

In a separate encampment, protesting women in billowing black robes and face veils huddled together as their children played nearby. In deeply traditional Yemen, particularly the northern swathes of the country, men and women are not to mix in public and indeed. The sight of women demonstrators -- now a regular sight -- has already challenged Yemen's deeply conservative society.

Over the past month, security forces have killed 48 demonstrators, according to a Yemeni rights group. Most of those were in the port-side province of Aden.