Armed tribesmen killed two soldiers and wounded another in an attack Saturday on oil installations operated by Norwegian DNO in southeastern Yemen, a security official said.
The assailants targeted a guardpost at the oil field in the Ghayl Bin Yamin district of Hadramawt province, the official said, accusing a regional tribal alliance of being behind the attack.
The recently formed alliance, which is behind strikes and protests in the province, issued a statement on Friday ordering DNO to stop operations by Saturday.
The statement warned DNO that it "will be held responsible for the result" if it refused to do so.
Hadramawt has been shaken since December 20 by protests against the central government after the army killed tribal chief Said Ben Habrish and his bodyguards at a checkpoint.
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On Monday, officials said tribesmen blew up a major oil pipeline linking the Masila field to Al-Daba port, in the town of Shahr on the Gulf of Aden.
The attack came as people in the province responded to calls for a general strike.
Attacks on oil and gas pipelines in Yemen are frequent. Oil Minister Ahmad Dares said last month that sabotage had cost the country $4.75 billion (3.5 billion euros) between March 2011 and March 2013.
Hadramawt was part of the formerly independent South Yemen, which was unified with the north in 1990.
A secession attempt four years later sparked a brief but bloody civil war that ended with northern forces taking over the south.
Southern grievances have hindered the political transition following the 33-year rule of Ali Abdullah Saleh, who stepped down last year following Arab Spring-inspired protests.