SANA'A // Sheikh Naser Musleh Nasm, an opposition activist, was killed yesterday in a gun battle with supporters of Yemen's president, Abdullah Ali Saleh.
According to tribal sources, Sheikh Nasm, a leading member in the Islah opposition party, was shot dead in the northern tribal province of al Jawf by supporters of the General People's Congress, Mr Saleh's party. Security officials also confirmed the death.
After Sheikh Nasem was killed, security forces and Saleh supporters surrounded a government headquarters that the pro-democracy protesters have controlled since Monday.
Demonstrators took control of the building on Monday after police opened fire on the protesters, wounding 20 of them. Al Jawf is a key town controlled by al Houthi rebels.
Last month, the rebels joined the anti-Saleh protests that erupted across the poverty-striken country in January and gained momentum last month. Protesters are calling for an immediate end to Mr Saleh's 32-year rule.
Meanwhile, in the central province of Mareb, armed men from al Shabwan tribe sabotaged a pipeline that carries the oil from Mareb to the Ras Eisa port on the Red Sea, tribal sources said.
The explosion occurred late on Monday and caused heavy damage to the pipeline - which carries 120,000 barrels per day. Oil production from two oil fields were halted because of the attack, according to media reports.
The Austrian energy group OMV said yesterday it would not be able to transport oil through the pipeline for the next two to three days.
"Because we are not the operator of this pipeline, we cannot give any information about the incident," a OMV spokeswoman, Michaela Huber, said in a statement.
Al Shabwan tribesmen had been camped out near the pipeline since Friday, demanding that Mr Saleh identify the killers of Jabir al Shabwani, a former deputy governor of Mareb. Mr Shabwani was killed in May 2010 in an air strike that targeted al Qa'eda suspects in Mareb; he had been negotiating with militants in an effort to convince them to surrender to the government.
Anti-Saleh protests took place in about 15 provinces yesterday. Tens of thousands participated in Ibb province after the funeral of protesters who were killed in Sana'a last month.
In the capital, 12 MPs who recently resigned from the ruling party joined demonstrations.
A group of young protesters, known as "peaceful change youths", lashed out at what they said was the international community's lack of response to the protests.
In an e-mail yesterday, the group called for an "open and clear position" towards attacks on protests that use "live fire and poison gas". The government has denied the use of lethal gas and has formed a committee to investigate the claims of field medics and protesters.
The protesters also criticised a statement by Gerald Feierstein, the US ambassador to Yemen, who said this week that Mr Saleh's departure would not solve Yemen's problems. He called for dialogue aimed at reaching a peaceful transfer of power.
"We reject any dialogue that would not lead to achieving our primary demand of toppling the regime and its trial as well as restoring the power of the people looted by president Saleh and his family for 33 years," the group said.
According to local rights groups, 47 people have been killed and more than 1,500 injured since the protests began in February.