Police are investigating The Times over claims that it hacked emails, it emerged Thursday, following the scandal over phone hacking at its sister paper the News of the World.

The revelation follows the admission by the editor of The Times, James Harding, to an inquiry into press ethics last month that one of his journalists had hacked the email account of a police blogger to try to expose his identity.

Labour MP Tom Watson wrote to London's Metropolitan Police to complain about the newspaper's behaviour and on Thursday published the letter he received in reply.

"Thank you for your letter dated 23 January 2012, and the subsequent letter clarifying the position around the evidence given by The Times to the Leveson Inquiry," Detective Superintendent John Levett wrote to Watson on January 25.

"I write to reassure you that the concerns raised within your letters are under investigation and officers from Operation Tuleta are dealing directly with the victim."

Operation Tuleta is the Met's investigation into computer hacking, which has so far made one arrest.

It runs alongside the probe into phone hacking at the Rupert Murdoch-owned News of the World tabloid, which was shut in July after it emerged it had hacked the voicemails of hundreds of people, including a murdered schoolgirl.

News International, Murdoch's newspaper division which also owns The Times, said it had no comment on Thursday on the police investigation.

The Metropolitan Police spokesman confirmed it had received a letter from Watson and said officers investigating computer hacking were in touch with him, but said it would not be giving a "running commentary" on the probe.

In his appearance before the Leveson Inquiry into press ethics last month, the editor of The Times said one of the newspaper's reporters had been disciplined after hacking an email account.

"There was an incident where the newsroom was concerned that a reporter had gained unauthorised access to an email account. When it was brought to my attention, the journalist faced disciplinary action," Harding said.

"The reporter believed he was seeking to gain information in the public interest but we took the view he had fallen short of what was expected of a Times journalist."

The reporter, named as Patrick Foster, was issued with a formal written warning for professional misconduct and was subsequently dismissed from the newspaper for an unrelated matter.

According to a Times story on the affair, Foster hacked the account of detective Richard Horton as part of an attempt to expose him as the author of NightJack, a popular blog that gave a behind-the-scenes view of police work.

The policeman tried to block the revelation but a High Court judge ruled in 2009 that the story naming him was in the public interest.

The Leveson inquiry was set up by Prime Minister David Cameron to look into the culture, ethics and practices of the British press after the phone hacking scandal.