British Prime Minister David Cameron has defended his decision to hire a former editor of the now-closed tabloid newspaper at the heart of a British phone-hacking and bribery scandal.

Mr. Cameron told a special parliamentary session on Wednesday that Andy Coulson should be treated as “innocent until proven guilty” and that his actual work with the prime minister has not come into question. Coulson served as Mr. Cameron's communications chief before resigning in January. He is one of 10 people arrested in connection with the scandal.

British opposition leader Ed Milliband said the prime minister made a “catastrophic error in judgement” in hiring Coulson, saying every effort should have been made to uncover the facts. Mr. Cameron denies any wrongdoing, saying he had no evidence that Coulson was involved in the scandal at the time of his hiring.

Opposition parties also have criticized the prime minister's frequent meetings with executives from Rupert Murdoch's News Corporation, owner of the tabloid. Mr. Cameron disclosed last week that he met 26 times with Murdoch executives during his first 14 months in office, more than twice the number of his visits with other media organizations.

A British parliamentary committee on Wednesday criticized the British arm of Murdoch's media empire for trying to “deliberately thwart” the investigation in to the phone hacking case, and said the police investigation into the matter was a “catalogue of failures.” The scandal has already led to the resignations of London's top two police officers, Paul Stephenson and John Yates.

On Tuesday, Rupert Murdoch apologized before British Parliament, calling it the “most humble day” of his life. Murdoch insisted that he is not personally responsible for the scandal. Instead, he said the blame lies with the people he trusted to run the organization, as well as their subordinates.

While Murdoch's son, James, was testifying, a protester rushed the table and threw a shaving cream pie at the elder Murdoch. Police identified the pie thrower as comedian Jonnie Marbles. Murdoch was not hurt.

Murdoch shut down the News of the World tabloid last week after 168 years of publication when it was discovered that some of its reporters may have illegally accessed thousands of cell phone voice mails of celebrities, politicians, rival journalists and possibly murder victims. Some of the reporters allegedly paid police for information.

Wednesday, Australian Prime Minister Julia Gillard said Murdoch's local media holdings should face increased scrutiny to see if they have engaged in any similar wrongdoing. In the United States, the FBI has also begun a probe into whether Murdoch's employees tried to hack into the phones of September 11 terrorist attack victims and their families and tried to bribe police.

News Corporation executives deny wrongdoing in both cases, saying the scandal was limited to the company's British wing.