Two more journalists not connected to News International have been arrested by Scotland Yard officers investigating bribery and corruption.
The latest arrests mark a further widening of the Elveden investigation which has so far seen 40 arrests – 21 of which have involved journalists.
One of those arrested has been named as Sunday Mirror crime reporter Justin Penrose while the other has been widely named as Tom Savage, deputy editor of the Daily Star Sunday.
Last Wednesday, former Mirror journalist Grieg Box Turnbull became the first journalist not linked to The Sun or News of the World to be arrested as part of the Elveden probe.
This morning a 37-year-old man was arrested at his home in Kent and a 34-year-old man was arrested at his home in south-east London. Both men had their homes raided at around 6am.
They were arrested on suspicion of conspiracy to corrupt (contrary to the Prevention of Corruption Act 1906) and of the common law offence of conspiracy to cause misconduct in a public office.
The two are being questioned at police stations in Kent and south-east London.
The arrests are understood not to have stemmed from information released by News Corp's Management and Standards Committee.
The Met Police said in a statement: "Today's arrests relate to suspected payments to a public official and are not about seeking journalists to reveal confidential sources in relation to information that has been obtained legitimately."
Press Gazette understands there is growing nervousness on Fleet Street about the Elveden investigation.
One insider said: "Whistleblowers phone up national newspapers with stories and they generally want paying for them. Most journalists would have realised it was wrong to pay policemen, but not prison officers and other public employees. The fear is that this latest arrest could lead to more dominoes falling."
In written evidence to the Leveson Inquiry, former Mirror editor Richard Wallace said: 'On occasion we have paid public sector employees (connected with the health and prison services) for information".
The Elveden Inquiry has seen most arrests made under the obscure and previously little-used 1906 Prevention of Corruption Act. The act was previously barely mentioned in journalists' media law bible MacNae's and it is not something the PCC Editors' Code covers.
It has extended beyond police officers to include prison officers, NHS workers and other public employees.