Quetta, Pakistan - Gunmen assassinated a nationalist leader in Pakistan's insurgency-torn province of Baluchistan on Wednesday as he left his home on the outskirts of Quetta, police and relatives said.

Habib Jalib was secretary general of the opposition faction of Baluchistan National Party, which advocates greater autonomy for the southwestern province and campaigns peacefully for self-determination.

Relatives said Jalib, a lawyer and former MP, was going to drop his children at school when gunmen waiting for him outside sprayed bullets and fled on a motorbike.

"He expired on his way to hospital. The motorcycle riders managed to flee after the firing," Shah Nawaz, a senior police officer in the hospital, told AFP.

The shooting took place in the Sariab neighbourhood on the outskirts of Quetta, the capital of Baluchistan.

Police said the identities of the killers were not immediately clear, but that a manhunt had been launched.

Violence has surged this year in Baluchistan, which borders both Afghanistan and Iran. Human rights activists have raised concerns about an increase in targeted killings in the province over the past 20 months.

Shops and markets shut down after Jalib's killing. Authorities also closed Baluchistan University for two days in a bid to minimise violent protests.

Hundreds of people have died since Baluch rebels rose up in 2004 demanding political autonomy and a greater share of profits from the region's wealth of natural oil, gas and mineral resources.

The province is also rife with Islamist militancy and sectarian violence.