The UK's police watchdog has began an investigation into allegations that Scotland Yard used hackers in India to illegally spy on the email accounts of British journalists, environmental campaigners and activists.
The UK's Independent Police Complaints Commission (IPCC) appealed to a whistleblower, believed to be a serving or retired Metropolitan Police officer who had sent an anonymous tip-off about the hack earlier this year, to get in touch.
"These are clearly serious allegations and the IPCC is conducting a comprehensive investigation into the matters raised. This will be a complex investigation given the potential involvement of foreign participants," said IPCC deputy chairman Sarah Green.
"We would like to hear from the officer who brought these allegations to light or any other officers or police staff who may be able to provide information of use to the IPCC investigation," she added.
The IPCC had received an anonymous letter alleging that covert officers from the Mets National Domestic Extremism and Disorder Intelligence Unit (NDEDIU) had contacted Indian police officers for help to enlist the services of hackers.
The letter alleges the hackers accessed the email accounts of members of political and environmental pressure groups and journalists.
The Met Police said: "The IPCC made the Metropolitan Police Service aware of anonymous allegations concerning the access of personal data and requested the matter referred to them by the MPS. This has been done."
"The MPS is aware that the IPCC is carrying out an independent investigation."
"As this investigation is now in the public domain the MPS can confirm that all possible steps are being taken to ensure all relevant material and associated computer systems are preserved to assist the IPCC investigation."
The IPCC is also carrying out two related and ongoing investigations into allegations that paperwork relating to undercover policing kept by the NDEDIU was shredded in May 2014.
Kulsuma Aktergetty images