Tribal fighters in central Yemen have kept an oil pipeline ablaze and have damaged roads leading to it.
Officials say the sabotage occurred in Maarib province, where oil pipelines are repeatedly damaged. It is unclear if the damage was connected to anti-government protests, where for weeks opposition activists angered by corruption, poverty and a lack of political freedoms have been demanding an immediate end to Yemeni President Ali Abdullah Saleh's 32-year rule.
On Monday, Yemeni security forces used gunfire to disperse anti-government demonstrations in several parts of the country, triggering street battles with protesters.
In one incident Monday, Yemeni protesters tried to storm a local government building in the northeastern province of Jawf, prompting security forces to open fire. At least 20 people were injured in the fighting.
Elsewhere, Yemeni security forces opened fire at a large opposition rally outside a provincial government building in central Yemen's Marib province. At least 20 people were wounded, including Marib's governor, who was stabbed by an unknown assailant. He was flown to the capital, Sana'a, for treatment.
Police also opened fire to disperse protesters in southern Yemen's Taiz province, injuring three people.
Saleh has fired his Endowments and Guidance Minister Hamoud al-Hattar in apparent frustration at al-Hattar's failure to launch a government dialogue with the opposition. He replaced Al-Hattar with another minister, Hamoud Mohammad Abad.
Some information for this report was provided by AFP and Reuters.