Nearly a week of political and ethnic violence has killed at least 91 people in Pakistan's largest city.

Police say the bodies of at least 11 people who were shot or tortured to death have been brought to government hospitals in Karachi since Sunday.

Pakistani Prime Minister Yousuf Raza Gilani traveled to the southern port city and held talks with government officials in Sindh province on Monday. The prime minister said strict action should be taken against those responsible for the violence.

Hundreds of people have been killed in Karachi in recent months, in one of the worst waves of unrest there in years. Many of the killings are blamed on ethnic gangs linked to rival political factions such as the majority Urdu-speaking Muttahida Qaumi Movement and the Awami National Party of Pashtun migrants.

Meanwhile in the southwestern province of Baluchistan, authorities say gunmen set fire to at least 18 trucks carrying fuel for NATO forces in neighboring Afghanistan.

There were no reported casualties in Monday's attack.