Updated

Employees of Pakistan's state airline have called off a four-day strike that crippled air travel in the country after the resignation of the top company official.

The leader of the employee union for Pakistan International Airlines says their major demand was the resignation of the company's managing director. The official submitted his resignation Friday evening, prompting celebration among the strikers.

Union leader Sohail Baloch says they hope to have flights running again after midnight. The strike lasted four days and grounded more than 200 flights.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

KARACHI, Pakistan (AP) — A strike by employees forced Pakistan's state-owned airline to ground the last of its planes Friday, leaving thousands of passengers stranded and raising concerns that a prolonged standoff could spark serious unrest.

Four days into the strike, there was no sign of compromise.

In the southern city of Karachi, police charged toward striking workers, clubbing some before all dispersed, according to footage broadcast by a private Pakistani television station. One man in a brown tunic crouched on the floor cradling a bloody nose in his hands.

A spokesman for Pakistan International Airlines said police had to drive the strikers out of Karachi airport so that those willing to work could do so. "Now that the police have cleared them from the airport, we hope to resume operations," Mashhood Tajwar said

PIA is Pakistan's largest carrier and the main operator of domestic flights. At least 250 domestic and international flights have been canceled since the strike began Tuesday, Tajwar said.

No PIA flights were in the air Friday, and the carrier closed its main booking office in Karachi, Tajwar said. In previous days, PIA had managed to operate some flights.

Pilots and support staff went on strike Tuesday over a proposal to have the struggling carrier share routes with Turkish Airlines. PIA managers say the route-sharing idea will reduce financial losses, but strikers fear it will lead to job and pay cuts.

The strike is costing the airline roughly $6 million (500 million Pakistani rupees) a day, Tajwar said.

It has also dealt another blow to Pakistan's struggling economy, kept afloat by large loans from the International Monetary Fund. Perishable cargo, such as flowers and fruit, have been left to spoil. One analyst estimated export losses after four days at $20 million.

Pakistan's ruling party is trying to shore up the country's economy, which is wracked by inflation, chronic power shortages and other problems, but it has met resistance from allies and the opposition on pursuing major reforms, including a new sales tax. Subsidizing PIA and other loss making state-run businesses eats up a significant chunk of the government budget each year.

PIA bosses say the route-sharing idea could raise money for the struggling carrier, which has posted multimillion dollar losses for years because of bad management and competition from Gulf airlines. Carriers around the world have increasingly struck route-sharing deals to tap new markets without investing in extra planes and staff.

Management denies that there will be job or salary cuts, but strikers say they don't trust the promises and continue to be opposed to the deal.

Staff cuts may be inevitable as part of financial trimming at PIA, said Mohammad Sohail, the chief executive of Pakistani investment firm Topline Securities Ltd. He said the airline is significantly overstaffed compared with other carriers in the region.

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Vogt reported from Islamabad.