A police officer says armed clashes between supporters of two political parties have left 11 people dead and dozens injured in southern Pakistan.

Pir Mohammad Shah says the clashes broke out in the suburbs of Khairpur town on Saturday during the first phase of voting for local government positions.

Shah says 25 people from both sides were injured in the clash. He says army troops have been called in to control the situation.

Saturday was the first phase of a three-phase election in southern Pakistan's Sindh province and Punjab province in the country's east. Remaining phases will be held later this month and next month.

Clashes between political opponents are not uncommon in Pakistan.