Reporter Mark Daly was arrested in August

The National Black Police association (NBPA) described journalist Mark Daly as "heroic" for his secret filming at a Cheshire police training centre in which he posed as a recruit in order to get candid views from fellow trainee officers.

Five officers accused of making racist remarks in documentary The Secret Policeman - broadcast on Tuesday - have resigned from the Greater Manchester, North Wales and Cheshire forces and three others have been suspended.

But Mr Daly was arrested on suspicion of obtaining a pecuniary advantage by deception and damaging police property when his seven-month role as an undercover police recruit was exposed in August.

His (Daly's) work helped uncover the racism that still dogs the police service, and which is so readily denied by senior police officers across the country Ray Powell, NBPA

The BBC has said any pay Mr Daly received has been kept in a separate bank account and was to be returned to the force at the end of the investigation.

It has also offered to pay for damage caused to Mr Daly's bullet-proof vest, which was altered to hold a pinhole camera and battery pack.

Integrity testing

The NBPA has demanded a public inquiry into police recruitment processes.

President Ray Powell said: "We feel very strongly that the individuals concerned were allowed to resign rather than be sacked, which would have sent out a much stronger message."

"Mark Daly was extremely brave in undertaking this and the Association of Chief Police Officers (Acpo) should thank him for exposing the problem.

Can you test for racism?

"He was exposed to a random environment within the police and encountered a number of clearly racist officers, so what's going on elsewhere?"

The body, which has previously opposed "integrity testing" to spot racist recruits, is now urging Acpo to "use whatever means possible to identify and eradicate these people".

Prime Minister Tony Blair also said he was "appalled and shocked", by what he saw in the documentary.

Speaking at his monthly press conference on Thursday, Mr Blair press that the "vast bulk" of police officers were "not in any shape or form racist" and urged that they should not be tainted by the actions of a small minority.

Informers

"It's just important that when a shocking report, and it is shocking, comes forward like this that we keep that sense of perspective and balance," he said.

The first officer to resign after the programme was screened, was Pc Robert Pulling of North Wales Police, who was shown dressed in an improvised Ku Klux Klan hood and making a string of racist comments.

He was followed later on Wednesday by Pcs Carl Jones, Tony Lewin and Adrian Harrison of Greater Manchester Police, and Pc Steve Salkeld from the Cheshire force.

Pcs Andy Hall and Andy Turley of Greater Manchester and Pc Keith Cheshire of North Wales Police remain suspended while criminal and disciplinary investigations are carried out.

WATCH THE PROGRAMME Click below to watch extracts from the programme. Some extracts contain strong language The Secret Policeman

In the documentary, Mr Daly filmed Pc Pulling admitting being racist, voting for the British National Party and saying Hitler had the "right ideas".

Doreen Lawrence, mother of murdered Stephen Lawrence - who was referred to in racist remarks - told Channel 4 news she found the documentary "frightening".

"I was numb for ages after watching it."

She added: "We have come nowhere and I think the police have to take responsibility for that."

North Wales police said it would be writing to the Lawrence family to apologise for "obscene" comments Pc Robert Pulling, had made.

All three forces involved strongly condemned the behaviour shown on the programme, and promised to do more to banish racism.

Sir John Stevens, commissioner of the Metropolitan Police and the UK's top police office, this week revealed plans to plant informers in its own training classrooms to root out racist recruits.

Mr Daly, 28, joined Greater Manchester Police as a trainee officer and secretly filmed recruits at Bruche National Training Centre in Warrington, Cheshire.