KARACHI - Authorities barred Abdul Qadir Baloch, a Baloch rights campaigner, from leaving the country due to his alleged involvement in anti-state activities, sources said Thursday.

Qadir Baloch, known as Mama (uncle) Qadir, was stopped at Karachi airport as he was about to fly to New York, where he was due to attend a weekend conference on alleged rights violations in Balachistan and Sindh provinces.

Qadir is the founder of a pressure group working for information on people who have ‘disappeared’ during the long-running conflict between the Pakistani government and Baloch insurgents.

Hundreds of people accused of links to insurgents have gone missing in recent years, allegedly at the hands of Pakistani security forces.

Many, including Qadir's own son, show up dead, but many are simply never seen again.

Last year Qadir led a group of families with missing relatives on a gruelling 2,000-kilometre march to raise awareness of their cause and demanding answers from the government.

The Federal Investigation Agency (FIA) confirmed to AFP its officers had stopped Qadir and his companion Farzana Majeed, whose brother is one of the missing, because they are on the government's ‘exit control list’ (ECL) of people barred from leaving the country.

Majeed said she had visited Dubai only a month ago without any problem.

"But last night we went to Karachi’s Jinnah International Airport, but after check-in, members of FIA told us: 'You are on the ECL, you people are in anti-state activities so we cannot let you (go)'," she told AFP.

"I am not an anti-state activist, I am only a human rights activist."

The security services say they are battling a fierce rebellion in the province, which is also an important smuggling route for heroin from Afghanistan.

Balachistan, the size of Italy and rich in copper, gold and natural gas, is Pakistan's largest but least populous province.