Pakistani authorities say they have buried a tribal leader, whose death during a military operation last week sparked violent protests.

Pakistani government officials confirmed the burial took place early Friday, amid tight security in the southwestern province of Baluchistan.

Nawab Akbar Bugti was killed last Saturday during a military raid on his mountain hideout.

Bugti's son says the government conducted the funeral without the family's permission and refused to let them inspect the body. No family members attended Friday's burial.

Witnesses say the coffin was sealed with at least two locks before being hastily buried.

A local cleric was reportedly the only person allowed to identify Bugti's badly decomposing body.

Pakistani lawyer and human rights specialist Hina Jilani says the rush to bury the body could be part of an official effort to cover-up an extra-judicial killing.

"The body will reveal the kind of death Akbar Bugti met with," she said.  "That's the main reason why nobody has had an opportunity to look at him.  We fear that it will reveal something that may very well be akin to a massacre and amount to very serious crimes."

Jilani, along with other critics of the Pakistan government, insists Bugti was a legitimate opposition leader killed because he challenged government policy in Baluchistan.

The 79-year-old Baluch nationalist was a key figure in the province's long-standing and often violent campaign for greater autonomy and greater control over local resources.

The government claims Bugti died when the cave he was hiding in collapsed during a gun battle with government security forces. Pakistani authorities have described him as a terrorist, and say he was responsible for a number of attacks on security forces and installations, such as gas pipelines. 

More than 10,000 people attended a public memorial service, held for the nationalist leader earlier this week in Baluchistan's capital city, Quetta.

The region was rocked by massive protests and sometimes violent riots following Bugti's death.

Jilani says Friday's funeral is unlikely to ease tensions in the area.

"I don't think things are going to end here," she added.  "The manner in which the burial has taken place has been extremely offensive to the people and they're not going to forget it."

Bugti's supporters say they are planning more demonstrations in the coming days.  Political opposition leaders in Islamabad are demanding an independent investigation into Bugti's death.