The killing comes after the arrest of at least 80 people this week in security sweeps against separatists in south Yemen, as the government reacted to a week of unrest in which army positions came under fire and northern-owned shops were burned.
Witnesses said they heard heavy gunfire on Thursday from gunmen thought to belong to a separatist militia, and later saw the 45-year-old officer slumped over his motorcycle in Zanjibar in Abyan province, the defense ministry's online newspaper said.
It added that the officer had previously received threats from members of the militia, led by a separatist leader formerly loyal to the government, but gave no further details.
Yemen, in addition to its conflict with separatists, is also facing a northern Shiite insurgency and a resurgent Al-Qaeda, whose Yemen-based regional arm claimed responsibility for a failed December bomb attack on a US-bound plane.
Western governments and neighboring Saudi Arabia, the world's biggest oil exporter, fear Al-Qaeda is exploiting the instability in Yemen to recruit and train militants to launch attacks in the region and beyond. People in south Yemen, home to most Yemeni oil facilities, complain that northerners have abused a 1990 agreement uniting the country to grab resources and discriminate against them.
The latest tensions flared in southern Yemen when a separatist protester was killed on Feb. 13 after police opened fire at a demonstration. Six others were injured. Later, police clashed with demonstrators who came to claim the protester's body for burial, igniting unrest in which separatists burned northern-owned shops and tried to block a road linking Lahj province to the main southern city of Aden, residents said.
Separatists killed two people including a senior police official a week ago in an ambush. Two policemen were wounded in an attack by gunmen in the town of Dalea the following day, and on Monday a military officer was killed in south Yemen.
