JOS, Nigeria (Reuters) - The Nigerian military fired in the air to contain violence in the central city of Jos on Saturday, after the killing of a Muslim man triggered a rampage by an angry mob, an army spokesman and witnesses said.

Four others died in the unrest, underscoring continued tensions in the region at the crossroads between Nigeria's Muslim north and Christian south. Sectarian clashes have killed hundreds of people this year.

A mob began rioting after the body of a Muslim man, who had apparently been strangled, was dumped in a sack on a main street, according to the military taskforce (STF) set up to police Jos and the surrounding area after clashes in January.

"When the Muslims discovered the body, they took to the streets and barricaded roads, stabbing passers-by indiscriminately," STF spokesman Donald Oji said, adding that three of those attacked had later died in hospital.

A fifth body was later discovered by soldiers on the other side of the city, he said.

Fierce competition for control of fertile farmlands between Christian and animist indigenous groups and Muslim settlers from the north have repeatedly sparked violence in central Nigeria's "Middle Belt" over the past decade.

Security forces say they have the situation under control, maintaining a night curfew in Jos. But killings have continued, raising fears of a repeat of clashes between Muslim and Christian mobs which killed hundreds in January and March.

Sporadic violence killed at last nine people last week, seven of them discovered in shallow graves around 30 km (20 miles) south of Jos. Residents said they were killed after stopping at a roadblock set up by a local gang.