A member of Home Office immigration staff has been arrested and bailed on suspicion of immigration offences.
The official was later detained again alongside three other members of immigration staff on suspicion of misconduct in a public office and conspiracy to steal.
The four suspects were held on December 6 by the Home Office Anti-Corruption Unit, which has the same powers of arrest as police constables.
The arrest in relation to immigration offences, first reported by The Sun, was confirmed by the Home Office on Thursday.
All four members of staff detained on December 6 have been released pending investigation and immediately suspended, according to the department.
A Home Office spokesperson said: “On December 6, the Home Office Anti-Corruption Unit arrested four members of immigration staff on suspicion of misconduct in public office and conspiracy to steal. They have been released pending further investigation and were immediately suspended.
“One officer arrested as part of the conspiracy had previously been arrested and bailed on immigration offences.
“We expect the highest standards of our staff. As soon as we are made aware of allegations of wrongdoing, they are rigorously investigated and we do not hesitate in taking decisive action.”