Robert Pulling of North Wales Police, who was shown dressed in a Ku Klux Klan-style hood, making racist remarks to a BBC undercover reporter, was the first to resign on Wednesday.
The police officer also admitted voting for the ultra rightwing British National Party (BNP), saying that Hitler had had the "right idea''.
Three unnamed officers from Greater Manchester police and a police constable (Pc) from Cheshire police resigned, following the screening of the BBC documentary.
Two other officers from North Wales Police and two from Manchester police have been suspended after making racist remarks on the documentary.
Britain's interior minister, Home Secretary David Blunkett, said the racism shown by the police officers was ''horrendous'' and urged better training for recruits.
The deputy chief constable of North Wales Police admitted the actions of his officers made him feel ''physically sick''.
"This is a big wake up call for us and I know that we will leave no stone unturned in rooting these people out"
deputy chief constable, Manchester Police
He also disclosed that Pc Pullings had been suspended previously because of concerns about his attitude.
Deputy Chief Constable Alan Green of Greater Manchester Police condemned the behavior of his officers and said:
''This is a big wake up call for us and I know that we will leave no stone unturned in rooting out these people''.
This latest incident once again turns the spotlight on racism in British police forces, which are still recovering from the findings of the Macpherson report in 1999. It branded the Metropolitan police as being institutionally racist.
The Macpherson report was commissioned following the murder of a black teenager, Stephen Lawrence, who was stabbed to death in a racist attack at a bus stop in Eltham, southeast London on 22 April 1993.
The report highlighted the shortcomings of the Metropolitan police in investigating the murder, on the grounds that the victim was a black.
The report urged police forces across the country to invest in better race and diversity training for all officers.
Imran Khan, a leading civil rights solicitor in the UK told Aljazeera.net he was shocked and appalled by the behaviour of the police officers.
''Serious questions need to be asked about the behavior of these individual police officers.
This documentary indicates that there are many more police officers out there who hold the same racist views towards black and Asian people,'' he said.
Last month, the National Black Police Association (NBPA) announced it would actively discourage black and Asian people from joining the police, following a number of high-profile complaints of racism within the police force by officers.
Sir John Stevens, Commissioner of the Metropolitan Police has announced the Met intends to place informers in its own training classrooms to name and shame racists.
Sir John added: ''I have never seen that type of conduct or behavior and that type of racism - if I had, I would have arrested them for it.''