Camden Council will be forced to spend hundreds of thousands of pounds to protect empty homes unless a “lunatic” ruling forcing them to provide squatters with a list of vacant properties is overturned, officials warn.

The council already spends up to �300,000 a year on 121 live-in “guardians” – young professionals who pay limited rent to live in “high risk” properties on a temporary basis until they are rented.

But this would rise vastly if details of all of Camden’s 500 empty properties have to be made public.

Judge Fiona Henderson recently ruled that Camden must release the list under the Freedom of Information Act.

But just days after the ruling, a newly decorated council house was invaded by squatters who had just been ordered to vacate a West Hampstead property owned by a doctor and his heavily pregnant wife.

The decorated council house had been recently allocated to a single mother and her four children.

Four police officers, a council official and a locksmith were drafted in to break down the door only to find it had been vacated overnight.

Cases like this fuel the council’s determination to appeal Judge Henderson’s ruling.

The council argues that it would spell social and financial disaster if it gave in.

Housing boss Julian Fulbrook said that the ruling to reveal the list was a “lunatic decision” which has left authorities across London “open jawed”.

He added: “I said, appeal at once. I did ask a second question ‘How cost-effective is an appeal?’ and I was told we were going to take this all the way.

“I was immediately reassured by my top housing team that the amount of money we could haemorrhage on any scale on Camden council housing would dwarf any sums that we would spend on the fanciest lawyers in the country.”

Due to the high turnover of council properties, officials say that any list would be out of date within a day of its release, risking squatters targeting vulnerable tenants in recently empty properties.

Another fear is that homes will be squatted in while older tenants are in hospital for long spells.

Camden’s assistant director of housing, David Padfield, said the borough has seen squatting numbers soar in the past six months. He will be directly involved in deciding Camden’s next move if the appeal is lost.

“We will be forced into spending more money on putting more guardians into vulnerable properties,” he said. “On top of that, things like grills on windows and big steel doors cost money and are very unsightly.

“Then, if those properties do end up with squatters, we have the rigmarole of the legal process, court time and then the process of eviction, tying up council officers and bailiffs.”

The council has until October 4 to appeal the legal decision.