An investigation has been launched after two immigration staff working with asylum seekers were revealed to be members of the far-right British National Party.
The two employees worked as guards in a detention centre but were unmasked when a list of BNP members appeared on the internet in November.
After the list was made public, one resigned and the other was suspended, a UK Border Agency spokesman said.
The guards' BNP affiliation was revealed when a list of members was leaked on the internet. The Border Agency is now investigating how the two staff - who were employed on behalf of the Home Office by a private contractor - managed to slip through the net.
The contractor is investigating the case of the suspended guard, who will not be able to work with refugees or enter any immigration building during course of the probe.
Today's revelation will add to long-standing fears that race-hate extremists are working within the immigration system.
One newspaper claims to have uncovered nearly 300 allegations of brutality by private security and immigration staff over the past two years.
Of these complaints, all made by asylum seekers, 38 were claims of racism, with refugees being called 'monkeys' and told to 'go back to their own countries', The Independent said.
The BNP wants immigration halted, all 'criminal and illegal immigrants' immediately deported, and for all others 'a system of voluntary resettlement ... to their lands of ethnic origin'.
Its policy states: 'We will also clamp down on the flood of "asylum-seekers", all of whom are either bogus or can find refuge much nearer their home countries.'
The Border Agency spokesman said today: 'There is no place for racism in the immigration system,' said.
'We ask anyone carrying out duties on our behalf to sign a declaration stating they are not a member of the BNP, the National Front or Combat 18.'
However, only the police and the Prison Service treat BNP membership as grounds for dismissal.
Labour MP Diane Abbott said last night: 'If it is true that staff employed to work with asylum-seekers and immigrants are members of the BNP then it is yet another sign that the Home Office are allowing for the mistreatment of immigrants in this country.
'For years, campaign groups and my colleagues and I have been pointing out that hiring private contractors to work as immigration guards is a bad idea. It seems we will now have more proof of this.'