A British police officer suspected of leaking information about the police's phone-hacking investigation to a newspaper had been arrested, the Metropolitan Police announced on Friday.

The 51-year-old officer was arrested at work on Thursday afternoon and has been bailed until September 29 when further inquiries will be started.

The Met's Deputy Assistant Commissioner Sue Akers said the officer's arrest was "hugely disappointing," but did not disclose the name of the arrested officer.

He was held on suspicion of leaking details to an unnamed newspaper which was referred to as the Guardian in the reports of Sky News.

"I made it very clear when I took on this investigation the need for operational and information security, " said Akers, who is leading the hacking probe. "The MPS (Metropolitan Police Service) takes the unauthorized disclosure of information extremely seriously and has acted swiftly in making these arrests."

Commenting on the arrest, the Guardian said in a statement that on the broader point raised by the arrest, journalists would no doubt be concerned if conversations between off-the-record sources and reporters came routinely to be regarded as criminal activity.

The Metropolitan Police said all officers working on the phone hacking investigation had signed a confidentiality agreement.

The Metropolitan Police has been investigating illegal hacking of the mobile phone voicemails by reporters from the now-defunct News of the World newspaper.

Xinhua