Islamabad, Aug 17 - Chief of the banned Pakistani outfit Sipah-e-Sahaba and religious scholar Sher Ali Haideri was gunned down along with an associate early Monday, triggering protests in several Sindh towns, including Karachi, police said.

Haideri, a renowned religious scholar, was returning to his hometown Khairpur in Sindh province from a ceremony in Pir Jo Goth when he was attacked, Online news agency quoted district police officer Pir Mohammad Shah as saying.

The attackers sprayed bullets on his vehicle killing him and his assistant Imtiaz Phalphoto on spot, Shah said. Six people were also injured in the attack.

Haideri's guards retaliated, killing an attacker, while the other assailants managed to flee the scene, the officer said.

Haideri's killing could be the result of personal enmity, Shah said.

After the government banned the Sipah-e-Sahaba, Haideri had floated the Millat-e-Islamia that was also banned.