Cricketer-turned-politician Imran Khan's Pakistan Tehreek-i-Insaf (PTI) party, protesting since August against the alleged rigging in the 2013 parliamentary election, Monday imposed a shutdown here.PTI activists have gathered at various locations here, where they burnt tyres and blocked 18 areas, closing down vehicular traffic, Dawn online reported.The blocked areas include Mall Road, Liberty Chowk, Bhutta Chowk, Town Hall Chowk and the area outside the Punjab Assembly.In response, the ruling Pakistan Muslim League-Nawaz (PML-N) has asked its members and officer-bearers in Lahore not to come out on roads in order to prevent violent clashes.While police have been told to act if the PTI tries to forcibly shutdown markets, Khan has said his party's protest would be peaceful.On Dec 12, PTI successfully imposed a shutdown in the port city of Karachi.PTI's earlier shut-down in Faisalabad Dec 8 resulted in the death of a party activist during violent clashes with PML-N supporters and police.