A team of undercover private detectives is being employed by a south London council to act as independent witnesses to incidents of racial harassment. They will be called on to give evidence in court when vic-tims are unwilling to do so themselves through fear of retaliation.

Lewisham council took the step in order to tackle cases of racial harassment involving tenants, around 120 at any one time, which the housing department has on its books . It modelled the scheme, believed to be the first of its kind in London, on a project pioneered by Sunderland council in the North-east.

The council, which refuses to discuss the cost of the contract, details of the firm of private investigators or exactly where it will operate, due to what it calls the 'delicacy of the operation, said it chose the firm after a 'careful trawl of people with relevant expertise. It also drew on the experience of Sunderland council.

One part of the borough the council says it has concentrated on in the past is the Silwood estate in the north of the borough, part of Surrey Docks which straddles Rotherhithe, Bermondsey and Deptford.

At the end of June there were 25 outstanding cases of harassment connected with Silwood. A total of 32 per cent of the estate's population is from ethnic minorities, compared with 20 per cent from ethnic minorities in Lewisham as a whole. The largest ethnic minority group on the estate is Afro-Caribbean.

A spokesman for Lewisham said: 'Reported harassment has ranged from anything from name calling, particularly name calling of children, to pushing things through doors to physical attack. 'It is clearly organised in that it is small groups of people who are the perpetrators. But there does not seem to be any political motivation for the harassment.

The spokesman said Lewisham would be bidding for money from the Government's single regeneration budget to keep the scheme going.

Previously, the council has had to resort to injunctions to stop harassment. This has not been enough to get those responsible evicted from council property. With the help of the private detectives this will now be possible. 'One of the things the private detectives will be doing is building up a dossier of information that our people can refer to, said the council spokesman.

Liberty, the civil rights organisation, welcomed the initiative but warned of the dangers of employing independent bodies which were not accountable.

''It is good that the council is doing more about racial and sexual harassment, but it is no good fobbing off the responsibility to private firms, said a spokeswoman.

Though London councils are increasingly turning to private detectives to track down lawbreakers, many have secretly used tracing agents for some time, for jobs such as credit reference checks.

Last month Lambeth openly acknowledged a pounds 500,000 contract for private detectives to catch council tax dodgers - the first London authority to do so.

Kensington and Chelsea has also decided to employ a private firm to investigate cases where tenants complain of racial harassment. But, instead of patrolling the streets, the firm will be based in an office, helping tenants in an advocacy role.