British detectives arrested a tabloid editor and three other journalists on Thursday over suspected phone-hacking at Trinity Mirror newspapers, widening the scandal that started at Rupert Murdoch's rival empire.
James Scott, the editor of weekly tabloid the People, and his deputy Nick Buckley were arrested along with the Sunday Mirror tabloid's former editor Tina Weaver and her former deputy Mark Thomas, the company and reports said.
Scotland Yard said three men aged 40, 46 and 49 and a woman aged 47, all current or former journalists, were arrested in dawn raids at addresses in London, without identifying them.
It said detectives on Operation Weeting, the probe launched in January 2011 into hacking at Murdoch's newspapers, "have identified and are investigating a suspected conspiracy to intercept telephone voicemails at Mirror Group Newspapers."
The new investigation focused on a period between 2003 and 2004 at the Sunday Mirror, the main competitor to Murdoch's News of the World tabloid, which closed in disgrace in 2011.
Police said the alleged crimes were "a separate conspiracy" to the investigations into phone-hacking and the bribery of public officials at News International, the British newspaper arm of Murdoch's News Corp empire.
A spokesman for Trinity Mirror confirmed Scott and Buckley were arrested as well as two former employees that it did not identify. An internal Trinity Mirror email cited by the Press Association news agency identified the other two as Weaver, who is reportedly heavily pregnant, and Thomas.
"The police are investigating allegations of phone hacking whilst they were on the Sunday Mirror during 2003 and 2004," Trinity Mirror said in a statement to AFP.
"We are cooperating with the police and we have no further comment to make at this stage."
Prosecutors said separately they had charged a former policeman with misconduct in a public office for selling information to Murdoch's daily tabloid The Sun.
James Bowes, 30, an ex-sergeant, sold details about three "high profile investigations" to The Sun in 2010 and was paid £500 ($746, 574 euros), the Crown Prosecution Service said.
Around 100 people have been arrested under various phone-hacking and corruption investigations sparked by the scandal at the News of the World.
Several people have been charged including Prime Minister David Cameron's former media chief Andy Coulson and former News International chief Rebekah Brooks.
Cameron also launched a judicial inquiry into the ethics of the press.
As news of the latest arrests broke, Cameron announced that cross-party talks to implement the recommendations of the Leveson Inquiry, including statutory regulation of the press, had broken down.
Trinity Mirror meanwhile said on Thursday that it had recorded a 75 percent slump in annual profits in 2012 to £706.5 million (818 million euros).
The company suffered a £12 million hit from the launch of The Sun on Sunday, Murdoch's replacement for the News of the World, and more than £1 million in costs from the Leveson inquiry.