By Syed Shoaib Hasan
BBC News, Islamabad
A top rebel leader from Pakistan's troubled province of Balochistan has been killed, his family says.
It is not clear where or how Mir Balaach Marri died
Mir Balaach Marri, alleged head of the banned Baloch Liberation Army (BLA), was killed in Afghanistan, Pakistani intelligence sources told the BBC.
The BLA and rebel tribesmen have been fighting Pakistani security forces for more provincial autonomy since 2000.
Nationalists say the mineral-rich province has been deprived of its rightful share of its own resources.
Mr Balaach's brother, Sardar Gazain Marri, said he had learnt of the rebel leader's death on Tuesday evening.
"Some of his comrades informed me he had been martyred," he told the BBC.
"I cannot disclose the location as it would further threaten the lives of those with him."
Sardar Marri says he believes his brother was killed in an army operation in Balochistan.
"I believe there were a clashes in the province on Tuesday in which Mir Balaach was killed."
However, intelligence officials in Pakistan told the BBC the rebel leader had been killed in Afghanistan.
They also declined to discuss the circumstances surrounding his killing.
Analysts say the killing could have been the result of a covert operation.
War and escape
Mir Balaach Khan Marri is said to have been the military mastermind behind the Baloch rebels.
Observers say the uprising could now be in trouble with the rebels' operational leader dead
The second son of one of Balochistan's premier tribal chiefs, Sardar Khair Bux Marri, Mir Balach Marri was a committed nationalist.
He resigned from the provincial parliament in 2003, complaining that Balochistan was still being deprived of its rights.
The province is Pakistan's largest, and its richest in natural resources. It has some of the biggest proven reserves of natural gas in the world.
There are also large deposits of gold, copper and other minerals.
The rebels say most of these resources are appropriated by the federal government, while locals are denied employment in regional projects.
All development indexes show Balochistan as the least developed of Pakistan's four provinces.
Nawab Bugti was killed last year
In 2000, the nationalists launched armed attacks to press for greater provincial autonomy. Pakistan's army replied with a massive military operation in the province four years later.
Over the next two years, hundreds of people were killed in clashes between the rebels and security forces.
Hundreds of thousands fled the area as fighting worsened.
The insurgency came to a climax in August 2006 when army troops surrounded several Baloch rebel leaders.
This included Mir Balaach Marri and veteran politician and former provincial governor Sardar Akbar Khan Bugti.
While Mr Balaach managed to escape along with several of his comrades, Nawab Bugti was killed. The clash also claimed the lives of dozens of army officers.
After that most rebels leaders are thought to have gone into exile in neighbouring Afghanistan.
But they continued to conduct raids into the region. In recent days, these had increased.
But observers say the uprising could now be in trouble with the rebels' operational leader dead.