A landslide has hit three makeshift homes in a slum in Pakistan's port city of Karachi, killing 13 people.

Senior police officer Javed Jaskani said a mass of mud and rocks crashed down a hill into camps in Karachi, the capital of southern Sindh province.

He said women and children were among the dead and injured.

State-run television said prime minister Nawaz Sharif expressed grief over the incident and instructed authorities to aid the families of the victims.

Karachi is Pakistan's largest city and many poor labourers working there live in slums and makeshift homes near surrounding hills.