After six weeks of confusion and delay, police insist they are poised to send a letter to more than 170 London newspapers outlining plans to crack down on editors who publish adverts for massage parlours that turn out to be brothels containing trafficked women.

In October, the we exclusively revealed police plans to get newspapers to stop running sex adverts.

This will start with a letter to editors asking them to co-operate.

If they do not comply it is believed police will attempt to prosecute editors and publishers whose papers run adverts for brothels found to contain sex slaves for aiding and abetting sex trafficking using new laws passed last year.

The story was based on reliable police sources and was welcomed by anti sex-trafficking campaigners and politicians in south London.

At the time, police were known to be working on a letter to be sent to editors detailing their plans.

However, within days the Metropolitan Police Service’s (MPS) press office was spinning the story, with the head of department Ed Stearns insisting to one editor that no letter existed.

A few days later, a member of his staff confirmed the existence of a letter and said it was being checked by the Met’s legal team.

But no letter was sent, with a range of reasons being suggested, from key people being on holiday to the need to get a large number of senior officers to sign it off.

Two weeks ago, Mr Stearns called Newsquest’s group editor for south west London and Bucks, Andy Parkes, admitting to the existence of the letter and confirming it would be sent to editors on November 22.

But Monday passed with no letter, fuelling fears the police might be watering it down under pressure from the newspaper industry.

But this week the press office insisted the letter would be sent out imminently.

A spokeswoman said: "Officers have seen from a considerable number of their investigations that advertising in newspapers can play a key role in facilitating the exploitation of trafficked victims for sexual services, with organised criminal networks seeking to advertise this crime through local newspapers or advertising journals.

"As a result, SCD9 [responsible for vice crime] is writing to editors of local London newspapers to ask them not to allow advertising space to be used to promote these practices.

"For the Croydon Guardian to suggest the MPS has been delaying sending the letter out is simply not true.

"We are committed to reducing the opportunity for criminal networks to continue their illegal activities and their exploitation of vulnerable people.

"This is just one way in which we are tackling this issue. The letter will be issued when it is ready, which is likely to be in the very near future."

Newsquest stopped running massage parlour adverts in 2008.

Campaign groups are delighted the police are fulflilling their promises to tackle the problem.

Denise Marshall, the director of charity Eaves Housing, which helps trafficked women, said: “We are really pleased that the police are committed to tackling editors who advertise brothels in their publications.

"By making it more difficult for men to buy sex, this initiative could have the power to reduce the number of women being exploited in prostitution.

"We fully support the police’s initiative and commend Newsquest’s commitment to the issue."

A CCAT spokesman said: “The Croydon Community Against Trafficking is deeply encouraged by the action the police are taking to enforce laws relating to the exploitation of people in our town and country.

“Human trafficking exists in our town, and indeed all around the UK and is largely evident in the exploitation of women, through sexual services they are forced to perform.”

Click here for our full coverage of the bid to cut out sex trafficking