British police widened a probe into alleged bribery by Rupert Murdoch's media empire Saturday, arresting five staff at The Sun tabloid, a member of the armed forces, a defence official and a policeman.

The arrests cast a shadow over the future of Britain's biggest selling daily, following the phone hacking scandal which led to the closure of its weekly sister paper the News of the World in July.

The arrested Sun staff were deputy editor Geoff Webster, picture editor John Edwards, chief reporter John Kay, chief foreign correspondent Nick Parker and reporter John Sturgis, a source with knowledge of the investigation said.

"I'm as shocked as anyone by today's arrests but am determined to lead The Sun through these difficult times," said Sun editor Dominic Mohan.

"I have a brilliant staff and we have a duty to serve our readers and will continue to do that. Our focus is on putting out Monday's newspaper."

News International -- the British newspaper arm of Murdoch's global media operation -- would not confirm reports that Murdoch was flying to London to reassure Sun staff that he would not close the paper down.

Scotland Yard said it had now broadened its investigation into alleged payments by journalists for information, which had previously focused on bribes paid to the police.

"The remit of Operation Elveden has widened to include the investigation of evidence uncovered in relation to suspected corruption involving public officials who are not police officers," it said in a statement.

It said five men aged 45, 47, 50, 52 and 68 were arrested in dawn raids at their homes in London and nearby areas on suspicion of corruption and of aiding and abetting misconduct in a public office.

In the first cases of their kind, a Ministry of Defence employee aged 39 was arrested at her home in Wiltshire, southwest England, and a 36-year-old man serving in the armed forces was arrested in the same area.

Both were held on suspicion of corruption, misconduct in a public office and conspiracy in relation to both offences.

All eight were still in police custody hours after their arrest.

Sky News said they were an army officer and his wife.

The Ministry of Defence said it would not comment on ongoing police investigations.

A police officer in the county of Surrey, which borders London, was also arrested on suspicion of corruption and misconduct in a public office.

Surrey police were responsible for investigating the 2002 murder of teenager Milly Dowler, whose phone was hacked by the News of the World after she went missing.

Police said they had completed a search of the offices of News International in Wapping, East London. They were also searching the homes of the arrested people.

The arrests were made following information provided to police by the Management and Standards Committee set up by Murdoch's US-based News Corporation, Scotland Yard said.

News Corp. confirmed that the five men arrested were employees of The Sun and that it had provided the information.

"News Corporation remains committed to ensuring that unacceptable news gathering practices by individuals in the past will not be repeated and last summer authorised the MSC to co-operate with the relevant authorities," it said.

Police have now made 21 arrests under Operation Elveden, including four current and former Sun journalists who were detained and bailed over alleged corruption in January.

Previous arrests in the bribery probe include Rebekah Brooks, the former News International chief executive, and Andy Coulson, the former spokesman for British Prime Minister David Cameron.

Police have also made 17 arrests in the separate investigation into phone hacking.

Murdoch shut down the News of the World amid public outrage and British media said there were fears among employees at The Sun that he could do the same thing to it.

The Australian-born tycoon bought The Sun in 1969 and it is the flagship of his UK newspaper operation, selling around 2.5 million copies a day with its diet of sex and scandal.

The editor of The Times newspaper, which is also owned by Murdoch, apologised on Tuesday to a blog-writing detective unmasked by a former reporter of the newspaper who allegedly hacked his email.