Cities across south Yemen were virtually paralysed Saturday by a second day of confrontations between southern militants and security forces in which 11 people were wounded.
As police said armed clashes broke out in several cities, medics said a militant wounded on Friday had died of his injuries.
Tension also spiked in the north, where the Sunni Islamist Al-Islah party accused Zaidi Shiite rebels known as Huthis of abducting one of its members as fighting raged.
And in the eastern province of Marib, saboteurs blew up two sections of an oil pipeline, the third time this week, and tribesmen attacked soldiers escorting technicians involved in repair work, officials said.
Attacks on oil and gas pipelines in Yemen are frequent. Oil Minister Ahmad Dares said this week that sabotage had cost the country $4.75 billion (3.5 billion euros) in the two years to March 2013.
Schools and public offices were closed and shops shuttered in the south on the second day of the week of protests launched over the death of tribal chief Said Ben Habriche, who was to be buried Saturday.
Four Southern Movement militants and two policemen were wounded in a clash in Ataq, capital of Shabwa province, police said.
Security sources said the militants had seized a rapid intervention force vehicle and police had to repel gunmen who briefly took over a telecommunications centre and an out-patient clinic.
In Huta, capital of Lahj province, five people were wounded in a gunfight, medical officials said.
Witnesses said the wounded -- a policeman and four passers-by -- were hurt when Southern Movement militants attacked a patrol in the city.
On Friday, a child and a southern militant were killed in the main southern city of Aden and in Mukalla, in southeast Yemen, medics and witnesses said.
And another southern militant who was wounded when police opened fire after a precinct in Aden was attacked, died on Saturday, medics said.
Ben Habriche was among six tribesmen killed on December 2 in fighting that erupted when his bodyguards refused to hand over their weapons to soldiers at a checkpoint. Two soldiers also died.
The tribal chief's funeral was due to take place in Mukalla where the Southern Movement said its supporters had taken over the city's police station "without clashes".
Most Mukalla residents stayed indoors and traffic was at a virtual standstill because of barricades of rocks and burning tyres set up by militants on main roads, witnesses said.
Protest organisers are pressing authorities to hand over the suspect who killed Ben Habriche, and to provide jobs for southerners in the police force, army and oil sector.
'Abduction' in the north
Following the end of British colonial rule in 1967, southern Yemen was independent until union with the north in 1990.
This was followed by a secession attempt in 1994 that sparked a brief but bloody civil war.
The conflict ended with an occupation of the south by northern forces that led to many of the disputes over land and jobs that still fan southern resentment.
Southern grievances are the main issue obstructing Yemen's national dialogue aimed at sealing a reconciliation following a 2011 revolt that led to the ouster of long-time president Ali Abdullah Saleh.
Authorities are also confronting an insurgency in the north, where Zaidis rose up against the central government in 2004, accusing it of marginalising them politically and economically.
The unrest in the remote Saada province has been compounded by sectarian fighting between the Zaidis and radical Sunni militants, with nine people reportedly killed on Thursday.
On Saturday Al-Islah, which includes radical Islamists involved in fighting the Zaidis, accused them of abducting its Saada representative, Sheikh Ali bin Ghaeb Zeid, and later said he was freed.
There was also violence in the capital Sanaa on Saturday, as police said they had seized a car packed with explosives and weapons after a firefight with two armed men inside the vehicle.
Both men were wounded in the clash, a defence ministry website quoted a police official as saying. One of the men died in hospital from his wounds, and security forces arrested the second.