Anti-government tribesmen in northern Yemen stormed a security building and shot dead four soldiers in a revenge attack after government troops opened fire on opposition protesters calling for the president's ouster, witnesses said.
The attack Monday night in the town of al-Jawf, close to the border with Saudi Arabia, was a significant escalation by the anti-government side in a month of daily street protests in which stone-throwing demonstrators have clashed with security. On the same day, a provincial governor was stabbed in the neck with a dagger during protests in the country's east.
The government's crackdown has also intensified with police firing on protesters and plainclothes government supporters attacking crowds with clubs and knives. Still, authorities trying to contain a month of protests set in motion by the tumult sweeping the Arab world have failed to restore order in Yemen, already one of the most impoverished and volatile corners of the Middle East.
The attack on the soldiers took place after troops opened fire on protesters rallying at the town's administrative complex, wounding 20 people. Those who witnessed the tribesmen's attack spoke on condition of anonymity because they feared for their safety.
The official Sabaa news agency put the number of soldier's killed at three, quoting a member of a government security committee in the capital, Sanaa. He was also quoted as blaming opposition parties and their allies.
President Ali Abdullah Saleh _ who has faced down threats from an al-Qaida offshoot, a secessionist movement in the south and a seven-year armed rebellion in the north _ has been unable to stop the protests, which are unprecedented in their scope and in the broad cross-section of society taking part.
The protesters, fed up with corruption, poverty and a lack of political freedom, have demanded that Saleh step down after 32 years in power and have rejected his offers to form a national unity government. Saleh also failed to appease the protesters with a pledge at the start of the unrest not to seek another term in office in 2013.
Saleh visited the governor of Marib province, who was stabbed and wounded by protesters on Monday, the official news agency reported. It said the governor's brother was also stabbed in the shoulder.
In more protests Tuesday, thousands poured onto the streets in the southern provinces of Taiz, Aden and Hadramawt.
In a separate dispute with the government, tribesmen in Marib province prevented oil workers from repairing an oil pipeline that was blown up on Monday, a security official said Tuesday. The sabotage of pipelines is one of the ways disgruntled tribesmen extract concessions from Saleh's weak government.
The security official said it was the third such explosion since May in retaliation for the accidental death of a provincial councilman in an airstrike targeting al-Qaida militants that was thought to have been carried out by a U.S. pilotless drone.
The official spoke on condition of anonymity because he is not authorized to brief the media.
The Yemeni government's cooperation with the U.S. in battling al-Qaida has angered many in Yemen.