Rival ethnic groups continued to clash in Pakistan's commercial capital Karachi on Monday in violence that has killed at least 32 people in three days.

Waseem Ahmed, the city's police chief, said 55 people have been injured in the clashes, which saw mobs attacking shops and setting fire to cars in different parts of the city.

The conflict is between the city's majority community of Urdu-speakers and ethnic Pashtuns from northwest Pakistan.

Tension has been high since leaders of the Urdu-speaking community said Taliban militants, most of whom are ethnic Pashtun, were gaining strength in the city.

Monday's riots forced authorities to close all educational institutions and postpone university exams.

With files from the Associated Press