People mourn next to coffins of their community members during a funeral ceremony in Quetta on October 4, 2011. – AFP

QUETTA: Pakistani police said Wednesday they had launched a crackdown on militants, detaining scores of suspects after being criticised for inaction over increased sectarian killings.

“We have rounded up about 100 people. They are being interrogated,” senior police officer Hamid Shakeel told AFP in Pakistan's southwestern province of Balochistan, where Shia Muslims have increasingly come under attack.

Residents said police conducted raids after hundreds of people staged a protest rally condemning police inaction.

Gunmen on Tuesday attacked a bus of Shias from the minority Hazara ethnic group on the outskirts of Quetta, the capital of Balochistan province.

The death toll from the attack rose to 14 as another victim died overnight, officials said. Two people are still in a critical condition in hospital.

On September 20, gunmen killed 26 Shia pilgrims after ordering them off their bus in Mastung district, then shot dead three of their relatives en route to collect the bodies.

Human rights organisations condemned the attacks and accused the government of not taking steps to prevent sectarian murders.

“The targeted killings of Shia are a barbaric attempt at sectarian and ethnic cleansing,” said Brad Adams, Asia director at Human Rights Watch.

“The government's failure to break up the extremist groups that carry out these attacks calls into question its commitment to protect all of its citizens,” he said.

Amnesty International said ethnic, political and sectarian killings raise “serious questions about the will or ability” of Pakistani security forces to protect the people of Balochistan.

The province, which borders Afghanistan and Iran, has become an increasing flashpoint for sectarian violence between majority Sunni Muslims and minority Shias, who account for around a fifth of Pakistan's 167 million population.

More than 4,000 people have been killed in outbreaks of sectarian violence since the late 1980s.