A former News of the World reporter has been quizzed by police over claims Tory communications chief Andy Coulson asked him to hack into phones when he was editor of the paper.
Sean Hoare's solicitor, David Sonn, said he was interviewed by Met Police officers under caution but was not arrested.
The phone hacking row erupted again earlier this month after Mr Hoare made the claims about Mr Coulson in an article in the New York Times.
Mr Coulson denies any knowledge of the practice which resulted in former News of the World (NotW) royal editor Clive Goodman and private investigator Glenn Mulcaire being jailed for accessing the voicemails of public figures.
In a statement, Mr Sonn said: "Sean Hoare, the journalist who was the subject of the recent New York Times article on phone hacking, was today interviewed under caution by officers of the Metropolitan Police at the offices of his solicitor David Sonn. Mr Hoare was not arrested."
Earlier, a Westminster sleaze watchdog announced it would consult parliamentary and legal experts on whether hacking MPs phones is a "contempt of parliament".
MPs voted last week to refer allegations that politicians' mobiles were targeted by newspapers to the standards and privileges committee.
After a preliminary meeting, the cross-party body of MPs said it would not consider any specific allegations until it had looked into the wider issues.
The decision to refer the case was led by Labour MP Chris Bryant who also issued judicial review proceedings over the row.
Asked if Mr Coulson was prepared to give evidence to the committee, the Prime Minister's official spokesman said: "Obviously the Government will cooperate with any inquiry."