A prison officer and a former Mirror journalist have been arrested in connection with the police probe into alleged corrupt payments to public officials.
Greig Box-Turnbull, 37, who worked for Trinity Mirror until taking voluntary redundancy in March, was arrested at his home in Morden, Surrey.
The prison worker, 46, was arrested at his home in south-east London, and a 50-year-old woman was held at a non-residential address in Kent.
They were all arrested on suspicion of corruption, conspiracy to commit bribery and conspiracy to cause misconduct in a public office.
Box-Turnbull is working for Westminster council but was on secondment to Richmond council.
A Westminster council spokesman said: "We have yet to speak to the employee. With the possibility of further legal action it would clearly be inappropriate to comment further."
Trinity Mirror has not been contacted by Scotland Yard about the arrest, and it is unclear whether any allegations are linked to Box-Turnbull's work for the Daily Mirror, a spokesman said.
So far 37 people have been arrested in connection with Operation Elveden, the investigation into suspected corrupt payments to public officials.