LONDON (AP) -- London's departing police chief revealed Tuesday that 10 of the 45 press officers in his department used to work for News International, but he denied there are any improper links between the force and Rupert Murdoch's media empire.

Paul Stephenson was giving evidence to a committee of lawmakers investigating wrongdoing at the now-shuttered tabloid News of the World, and allegations of bribery and collusion between Murdoch employees and the police.

``I understand that there are 10 members of the (Department of Public Affairs) staff who have worked in News International in the past, in some cases journalists, in some cases undertaking work experience with the organization,'' he said.

Stephenson denied wrongdoing, or knowing the newspaper was engaged in phone hacking _ but acknowledged that in retrospect he was embarrassed the force had hired a former News of the World editor as a PR consultant.

After being asked about his relationship with Neil Wallis, a former executive editor who was arrested last week, Stephenson said he had ``no reason to connect Wallis with phone hacking'' when he was hired for the part-time job in 2009.

He said now that the scale of phone hacking at the paper has emerged, it's ``embarrassing'' that Wallis worked for the police.

Stephenson announced his resignation Sunday, saying allegations about his contacts with Murdoch's News International were a dostraction from his job.

He was followed out the door by assistant commissioner John Yates, who will also give evidence Tuesday, befire a hotly anticipated appearance by Rupert Murdoch, his son James and the media mogul's former U.K. newspaper chief, Rebekah Brooks.

Rupert Murdoch's car was mobbed by photographers as he arrived for a grilling from U.K. lawmakers about the phone hacking scandal that has swept from his media empire through the London police and even to the prime minister's office.

The elder Murdoch's Range Rover was surrounded as he arrived at the Houses of Parliament three hours early, and it quickly drove off. It wasn't immediately clear if he had come back and gone through another entrance.

Politicians will be seeking more details about the scale of criminality at Murdoch's News of the World tabloid, while the Murdochs will try to avoid incriminating themselves or doing more harm to their business without misleading Parliament, which is a crime.