An undercover police officer who reportedly married an activist he was supposed to be spying on has been placed on restricted duties, police said.
Jim Boyling, a specialist operations detective constable with the Met Police, was an undercover officer deployed among green activists, the Guardian newspaper reported.
His ex-wife told the paper he encouraged her to change her name by deed poll in an unsuccessful attempt to conceal their relationship from senior officers.
A Met Police spokesman said last night: "A serving Metropolitan Police Service (MPS) Specialist Operations Detective Constable has today, Friday 21 January, been restricted from duty as part of an investigation by the Directorate of Professional Standards (DPS) following allegations reported in a national newspaper on Thursday 20 January.
"The matter will be thoroughly investigated by the DPS. As the allegation is subject to investigation, we are not able to comment further at this stage."
Pc Boyling is the fourth person to be identified as an undercover police officer deployed among environmental activists.
He was named by his ex-wife after claims that another spy, Mark Kennedy, had a number of sexual relationships while undercover with environmental protesters.
Pc Boyling's ex-wife told the Guardian she met him in 1999 when he was working to infiltrate the Reclaim the Streets environmental group under the alias Jim Sutton.
After he completed his undercover work he is said to have vanished for a year, before reappearing and admitting his real identity as a police officer.
The couple married and had two children before divorcing two years ago.