Undercover journalist Mark Daly's report has shocked senior police

Two are still suspended after the revelations contained in undercover documentary The Secret Policeman.

Police chiefs from the three forces involved have strongly condemned the racist behaviour shown on the film, and promised to do more to banish racism.

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.

Training

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.

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

Home Secretary David Blunkett said the racism was "horrendous" and urged better training for recruits.

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

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

North Wales Deputy Chief Constable Clive Wolfendale said the programme had made him feel "physically sick".

Deputy Chief Constable Alan Green of Greater Manchester Police said he had been "shocked, ashamed and very saddened" by what he had seen, and promised a full investigation.

Can you test for racism?

He said while the majority of his officers were hardworking and not prejudiced, "we need to do more" against racist officers.

Cheshire Assistant Chief Constable David Griffin said racist conduct, whether inside or outside the police service, was "abhorrent".

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