The Metropolitan Police authority agreed that Scotland Yard should pay the bill for former assistant commissioner John Yates to hire the high-profile libel firm Carter Ruck to threaten legal action against various media outlets including the Guardian, an FOI request has shown.

Yates, who resigned over the phone-hacking scandal last month, used the legal firm to send letters of complaint to the Guardian and other outlets over allegations made about his role in the affair. At the home affairs select committee he declined to say whether Scotland Yard had been paying for him to use the firm.

He said to the committee: "Contrary to what they may think, I have huge admiration for what the Guardian have done. It was a huge story."

In response to an FOI on the issue, the Metropolitan Police Service said on Wednesday: "We can confirm that the Metropolitan Police Authority authorised funding in order that the MPS could seek legal advice from Carter Ruck following an article in the Guardian newspaper concerning assistant commissioner John Yates.

"The MPA can approve expenditure on legal advice under strict criteria, subject to limits on the amount to be disbursed, for cases which have potential to bring the organisation as a whole into disrepute."

The Met refused to disclose how much had been paid to the law firm, and the details of the services for which the payments and costs were made, on the grounds that the data were personal and their release would breach the data protection act.

A spokeswoman for the MPA said: "The initial request for funding was turned down. Subsequent advice from the MPS was to the effect that the organisation's reputation was compromised and this led the authority to approve capped expenditure for legal advice. The authority was not sighted or consulted on which legal advisers would be engaged."

Yates also threatened legal action against the Evening Standard over allegations they made about the reason he did not pursue the phone-hacking review adequately. The Standard has since apologised, saying: "On 7 July we wrongly reported that Mr Yates had not properly investigated phone-hacking at the News of the World because he was afraid the newspaper would expose him for allegedly cheating on his wife. Mr Yates had at the time officially separated from his wife and was openly in a new relationship. We sincerely apologise to Mr Yates for any distress caused."

Yates, who was involved in some of Scotland Yard's most high-profile and politically sensitive inquiries, including the cash-for-honours scandal, resigned last month after coming under criticism for the way he handled the 2009 review of the original phone-hacking investigation and over his friendship with former News of the World executive Neil Wallis.

He decided to resign after the MPA made clear that they were going to suspend him from his post and refer his conduct to the Independent Police Complaints Commission.

The IPCC has since dropped its inquiry into Yates's handling of the phone-hacking review in 2009, saying there was no evidence that he had committed a disciplinary offence. IPCC deputy chairman Deborah Glass said he would face no further action in relation to it but said investigators had agreed with Yates's own admission that his decision not to review the hacking evidence in 2009 was "poor".

The IPCC is, however, carrying out an inquiry into whether he used his position to help get Wallis's daughter a job at Scotland Yard. He is accused of arranging a civilian role at Scotland Yard for Amy Wallis, 27.

Yates has said he is innocent and has expressed confidence that he will be exonerated.