All 19 stmembers at the Pakistani fast food chain, Johnny & Jugnu in Lahore were rounded up at 0100 (2000 GMT) on Saturday and held overnight for refusing to give free burgers to police officers who asked.

“This is not the first time something like this has happened… at our restaurant,” a statement by the burger chain said.

Nine police officers involved in the incident have now been suspended.

Senior provincial police official Inam Ghani announced the suspensions on Twitter, saying: “No one is allowed to take the law into his own hands. Injustice will not be tolerated. All of them will be punished.”

In a statement posted on Facebook, Johnny & Jugnu said a group of police officers had gone to the restaurant two days before the incident and asked for free burgers.

“Upon rejecting their request for free burgers, which has become a common practice for them, the police officers threatened our managers and left, only to return the next day to further harass and pressurise our teams… with baseless arguments,” the statement said.

On 11 June, it said, “some police officers came to our… outlet and took our manager into custody, without giving any reason whatsoever. Then they emptied out our entire branch, taking all of our kitchen crew, including the rest of the managers”.

The restaurant also said the staff were not allowed to close down the kitchen, leaving “fryers still running, customers waiting for their orders”.

The workers were detained for seven hours and said the officers were “harassing them, pushing them around, all for not giving them free burgers”.

Pakistan’s Prime Minister Imran Khan has previously called for a reform of the Punjab region’s police force, saying local politicians had appointed “cronies” to run police stations.