Pakistan Election Commission tonight announced to investigate allegations of rigging at many polling stations in the country's financial hub Karachi and warned that parties found guilty would have their results annulled.        

"We have received complaints about rigging from several constituencies in Karachi and Hyderabad and we will be investigating them," Chief Election Commissioner Fakhruddin G Ebrahim said.        

He said that re-polling will take place in more than 40 polling stations in NA-250 constituency in Karachi. It was alleged that at many stations there was no staff and ballot boxes were absent or snatched by miscreants. The EC has ordered that polling taking place in these constituencies be stopped immediately.