|Fighting between police and separatist fighters erupted after security forces put up checkpoints [EPA]
Two police officers have been killed and two more wounded in fresh clashes in southern Yemen.
The incident happened on Saturday just hours after the army killed at least one anti-government fighter, a local official and witnesses told the AFP news agency.
Four civilians were injured in the clashes.
Violence broke out at dawn after security forces put up a checkpoint outside Habilayn, in Lahej province, pitting Yemen's army against members of the separatist Southern Movement.
South Yemen, where many residents complain of discrimination by the federal government in Sanaa in the allocation of resources, was independent from 1967 until 1990 when it united with the north.
It launched an unsuccessful secession attempt four years later. Formed in 2009, the Southern Movement is a mix of secessionists and those who seek greater autonomy for the region.
Local officials and medics in Habilayn said on Friday that one fighter was killed and two others were shot and wounded in clashes.
However, a Southern Movement official said two of its members, hit by shrapnel, died in hospital after the army fired on a position held by the group on a mountain overlooking Habilayn.
Officials sources said that on Friday three soldiers were wounded when their patrol was ambushed by suspected Southern Movement members, and that the army set up the checkpoint after an army brigade commander, General Thabet Nasser al-Juhuri, survived two assassination attempts last week.
In the provincial capital of Huta, fighters attacked the local intelligence headquarters with machine guns and rocket-propelled grenades on Friday night, causing damage but no casualties, witnesses and a security official said.
Also on Friday, in the neighbouring Abyan province, armed men killed one police officer and wounded another in an attack on a security patrol, the Yemeni defence ministry's 26sep.net news website reported.