British Prime Minister David Cameron sought to distance himself from the resignation of the country's most senior policeman Monday, saying the London force's role in the phone-hacking scandal was quite different from that of the government.

Paul Stephenson quit as head of the Metropolitan Police on Sunday over his links to Neil Wallis, a former deputy editor at the Rupert Murdoch-owned tabloid, the News of the World. The London police force had hired Wallis as a public relations consultant.

Cameron hired one of the newspaper's former editors, Andy Coulson, as his communications chief after he resigned in 2007 over the hacking of phones of members of the royal family.

Asked at a news conference to explain the difference between Stephenson hiring Wallis and the prime minister hiring Coulson, Cameron said: "I don't believe the two situations are the same in any shape or form.

"There is a contrast with the situation at the Metropolitan Police, where clearly the issues have been around whether or not the investigation is being pursued properly.

"In terms of Andy Coulson, no one has argued that the work he did in government in any way was inappropriate or bad. He worked well in government, he then left government."

Coulson left his job as Cameron's media chief in January, raising questions about the prime minister's judgment in hiring him in the first place.

Cameron also defended his decision to travel to Africa on a trade mission, despite the growing row at home over hacking and illegal payments to police.

"Just because you are traveling to Africa doesn't mean you suddenly lose contact with your office," he said.

"I have had discussions with my own office, but also clearly with the Home Secretary to make sure that not only the Metropolitan Police Service does not miss a beat in this vital work, but the government is pressing ahead on all the fronts that it needs to," he added.

Cameron said he may call an emergency session of parliament Wednesday, the day after Rupert Murdoch, his son James and close aide Rebekah Brooks are due to appear before a parliamentary committee.