Scotland Yard has admitted it employed Neil Wallis, a former executive at the News of the World, as an adviser to the commissioner until September 2010.

Wallis was employed to advise Sir Paul Stephenson and John Yates on a part-time basis from October 2009 to September 2010. During this time the Yard was saying there was no need to reopen the phone-hacking investigation – a decision made by Yates despite allegations in the Guardian that the first police investigation had been inadequate.

Wallis is a former News of the World executive editor. He was arrested on Thursday morning as part of the police's renewed phone-hacking inquiry.

Wallis joined the News of the World in 2003 as deputy to then editor Andy Coulson. In mid-2007 he became executive editor, eventually leaving the News International title in 2009. Police say he supplied "strategic communication advice". The Met said his company was chosen because it offered to do the work for the lowest price. He was paid £24,000 by Scotland Yard to work as a two-day-a-month consultant.

Relations between senior Met officers and News of the World senior executives have been under scrutiny. In September 2006 Stephenson, as deputy commissioner, accompanied by the Yard's head PR man, Dick Fedorcio, dined with Wallis. This was a month after officers had arrested the paper's royal correspondent, Clive Goodman, and at a time when detectives were still attempting to investigate whether other journalists or executives were involved in the interception of voicemail messages. In theory Wallis was a potential suspect in the inquiry.

Scotland Yard said: "Chamy Media, owned by Neil Wallis, former executive editor of the News of the World, was appointed to provide strategic communication advice and support to the MPS, including advice on speechwriting and PR activity, while the Met's deputy director of public affairs was on extended sick leave recovering from a serious illness.

"In line with Metropolitan Police Service/Metropolitan Police Authority procurement procedures, three relevant companies were invited to provide costings for this service on the basis of two days per month. Chamy Media were appointed as they were significantly cheaper than the others. The contract ran from October 2009 until September 2010, when it was terminated by mutual consent.

"The commissioner has made the chair of the police authority aware of this contract."