LAHORE - A snap local election will be held in Pakistan's most populous province, officials said, after the provincial leader, an ally of ousted Prime Minister Imran Khan, triggered the poll, putting pressure on the government ahead a planned general election.

Holding local elections in a province with 110 million people, around half Pakistan's population, would be an expensive, logistically complicated exercise for a government dependant on foreign aid and reeling from the impact of last year's devastating floods.

By bringing forward a local poll, political analysts say it could pressure the national government into holding a countrywide election earlier to avoid the huge double cost of two votes.

Punjab is one of two provinces ruled by a coalition partner of Khan's Pakistan Tehreek-e-Insaaf (PTI) party.

Khan has been demanding general elections since he was ousted in April after losing a parliamentary vote of confidence. The 70-year-old former international cricketer has also led nationwide protests against his successor, Prime Minister Shehbaz Sharif.

Sharif has repeatedly rejected Khan's demands, saying elections will be held as scheduled later this year. As for the provincial assembly elections, Interior Minister Rana Sanaullah said the government will hold snap polls as necessary.

Punjab government spokesman Mussarat Cheema told Reuters the process to choose a caretaker government to oversee the polls had started. "We want this process to be completed as soon as possible so that we head toward elections," he said.

According to the constitution, the local assembly was automatically disbanded 48 hours after Punjab's chief minister called for it to be dissolved late on Thursday. The constitution also stipulates that elections must be held within 90 days.

Mahmood Khan, the chief minister of the other PTI-coalition ruled province, the northeastern Khyber Pakhtunkhwa, said he would call on Tuesday for the local assembly to be dissolved.

(Writing by Asif Shahzad and Miral Fahmy; Editing by Vin Shahrestani)