Fresh political violence in Pakistan's southern port city of Karachi has killed 11 people, while an explosion at a house has killed four people in the country's southwest.

Police said Thursday the violence overnight in Karachi erupted after a senior member of the ruling Pakistan People's Party criticized the rival Muttahida Quami Movement and its leader.

Authorities said they have arrested about 160 people following the fighting.

A surge in political and ethnic violence in the city has killed at least 100 people since last week.

Meanwhile, officials in the southwestern town of Chaman, along the Afghan border, said a blast ripped through a house used by Afghan refugees, killing four people and wounding 10 others.