WANA (Pakistan) - PAKISTANI authorities imposed a curfew in the main town of a violence-plagued region near Afghanistan on Wednesday after militants attacked a military post, as violence hit several other points across the country.

Militant violence has increased in nuclear-armed Pakistan over recent weeks while ruling coalition parties have been distracted by infighting and the resignation last week of staunch US ally Pervez Musharraf as president.

Political and security problems have undermined investor confidence and sent financial markets sliding as authorities struggle to control rising inflation and widening twin deficits.

Militants in the South Waziristan region attacked a military post east of the region's main town of Wana on Tuesday night. There were no immediate reports of casualties.

The government responded by imposing a curfew.

'The curfew has been imposed for an indefinite period,' said Mr Shahab Ali Shah, the top government official in the region.

Security forces were patrolling and had set up check points on main routes but witnesses said Taleban militants were ignoring the order and wandering around the town centre.

South Waziristan has been an area of militant activity for years, in particular since the U.S.-led ouster of the Taliban in Afghanistan in 2001 when thousands of al Qaeda and Taliban took refuge in semi-autonomous regions on the Pakistani side of the border.

Pakistani security forces have launched intermittent offensives aimed at clearing foreign militants out of the region and stopping cross-border militant attacks into Afghanistan.

But South Waziristan has been relatively quiet in recent weeks as the security forces focus on the Bajaur region and the Swat Valley, both to the northeast of Waziristan.

Blast in Islamabad
Separately, a blast at a roadside cafe on the outskirts of the capital, Islamabad, killed seven people and wounded 16 late on Tuesday, police and a hospital official said.

Police initially said the blast happened when a gas cylinder accidently exploded while about two dozen people were eating at small tables outside the cafe. They later said the blast had been caused by explosives but did not say it was a bomb.

Militants based on the Afghan border are waging a campaign of bomb attacks aimed at forcing the military to halt operations in Bajaur and Swat.

Last week, Pakistani Taleban claimed responsibility for an attack by two suicide bombers on workers outside the country's main defence industry complex which killed about 70 people.

Meanwhile, three students died in a gun fight at Karachi University as rival campus political groups battled, raising concern trouble could spill onto the streets of the volatile city.

Students from the Muttahida Qaumi Movement, a regional party that backed Mr Musharraf and has long controlled Karachi, fought with rivals from the conservative Islamist Jamaat-e-Islami religious party on Tuesday.

The head of the Jamaat-e-Islami, Qazi Hussain Ahmed, warned of riots in the country's financial capital, which has a history of bloody clashes between political, ethnic and religious rivals.

'It is a conspiracy to push the city into widespread street riots,' Mr Qazi said in a statement. -- REUTERS