Alan Johnson's ex-bodyguard has been suspended amid allegations that he had an affair with the former shadow chancellor's wife.
The episode led Mr Johnson to quit Labour's frontbench on Thursday, forcing leader Ed Miliband to reshuffle his top team less than four months into the job.
Close protection officer Pc Paul Rice guarded Mr Johnson when he was home secretary. He is thought to have worked for Theresa May since she took over at the Home Office last May.
In a statement, the Metropolitan Police said: "A Metropolitan Police Service Specialist Operations Police Constable has today been suspended from duty pending the outcome of the Directorate of Professional Standards (DPS) investigation into allegations reported in the media regarding an inappropriate relationship.
"The matter was referred by the MPS Specialist Operations Unit to the DPS on January 20. A thorough investigation is now under way. As the allegation is subject to investigation, we are not able to comment further at this stage."
Mr Johnson has refused to elaborate on the "personal reasons" for his shock resignation, saying only that he was finding it "difficult to cope" with "personal issues in my private life".
He has been married to Laura, his second wife, for almost 20 years. The couple have a 10-year-old son.
Mr Miliband reshuffled his shadow cabinet and installed Ed Balls as shadow chancellor after overlooking him last October.
Labour's deputy leader, Harriet Harman, insisted there would be no difficulties between Mr Balls and Mr Miliband despite their rivalries in the past.
Conservative Party deputy chairman Michael Fallon said: "Labour maxed out the nation's credit card and now can't agree on how to deal with their debt. Ed Balls can't escape his record, and now he can't escape this first question: would he stick with Labour's previous plan and start cutting in 10 weeks time, if so, what would he cut?"
Alan Johnson's ex-bodyguard has been suspended amid allegations that he had an affair with the former shadow chancellor's wife.
The episode led Mr Johnson to quit Labour's frontbench on Thursday, forcing leader Ed Miliband to reshuffle his top team less than four months into the job.
Close protection officer Pc Paul Rice guarded Mr Johnson when he was home secretary. He is thought to have worked for Theresa May since she took over at the Home Office last May.
In a statement, the Metropolitan Police said: "A Metropolitan Police Service Specialist Operations Police Constable has today been suspended from duty pending the outcome of the Directorate of Professional Standards (DPS) investigation into allegations reported in the media regarding an inappropriate relationship.
"The matter was referred by the MPS Specialist Operations Unit to the DPS on January 20. A thorough investigation is now under way. As the allegation is subject to investigation, we are not able to comment further at this stage."
Mr Johnson has refused to elaborate on the "personal reasons" for his shock resignation, saying only that he was finding it "difficult to cope" with "personal issues in my private life".
He has been married to Laura, his second wife, for almost 20 years. The couple have a 10-year-old son.
Mr Miliband reshuffled his shadow cabinet and installed Ed Balls as shadow chancellor after overlooking him last October.
Labour's deputy leader, Harriet Harman, insisted there would be no difficulties between Mr Balls and Mr Miliband despite their rivalries in the past.
Conservative Party deputy chairman Michael Fallon said: "Labour maxed out the nation's credit card and now can't agree on how to deal with their debt. Ed Balls can't escape his record, and now he can't escape this first question: would he stick with Labour's previous plan and start cutting in 10 weeks time, if so, what would he cut?"