A police station closed by the Mayor of London has been causing sleepless nights for neighbours – after its blaring alarm was left ringing for 48 hours with officers unable to turn it off.

Frustrated residents living near the former Hampstead Police Station were kept awake all weekend by its shrieking security system.

Police were inundated with complaints but officers seemed unable to do anything about the noise, as confusion reigned over who could shut it off.

Residents were told the matter was being looked into at a “high level” – while one was transferred to the Met’s lost property department by a hapless phone operator.

Christine Liese, 55, of Downshire Hill, said: “It was horrible – literally 48 hours with no sleep.

“The whole neighbourhood was trying to go through various channels to stop it, but they were either not responding or did not know what to do. It was rather hopeless.

“When I spoke to someone at the Met, they did not even know they had a property services department and put me through to lost property.”

The alarm started on Saturday morning and only stopped ringing on Monday lunchtime.

Ms Liese added: “They sent a car which accessed the building [on Saturday], saw nothing wrong and left, because they did not have the combination.”

Shana Ting Lipton, 41, a journalist of Downshire Hill, said: “The left hand didn’t seem to know what the right hand was doing, in terms of who was responsible and who had the key.”

She spoke to a police officer outside who told her: “I don’t know what to do, I can’t get in there.”

Speaking on Monday with the alarm still blaring, retired solicitor Teddy Bourne, 65, another Downshire Hill resident, said: “I have just spoken to the police who say there have been a number of complaints and it’s being ‘looked into at a senior level’.

“Obviously, so far it has proved too difficult to get someone there to turn it off.”

The episode added insult to injury for those who were incensed by the station’s closure in June.

With police seemingly powerless to turn off the alarm, residents said it was the Met’s estate agent, Knight Frank, who finally managed to deactivate the alarm.

Knight Frank is handling the sale of the Grade II-listed building, currently under offer.

A police spokesman said: “The siren was the building’s fire alarm, which seemed to have activated through a fault. The alarm has been silenced and the fault has been resolved.”