Editors Wallace and Weaver leave Daily Mirror and Sunday Mirror
The editors of the Daily Mirror and Sunday Mirror left "with immediate effect" today and the papers are moving to a seven-day publishing model.
Richard Wallace and Tina Weaver will be replaced by former People editor Lloyd Embley.
The move to a seven-day operation comes after tabloid rival The Sun launched a Sunday edition following the demise of the News of the World.
The company said the move was a "further step towards creating one of the most technologically advanced and operationally efficient newsrooms in Europe".
Mark Hollinshead, managing director nationals, said: "I'm delighted to appoint Lloyd to the position of editor of the Daily and Sunday Mirror. He is an accomplished editor who has done a first class job on improving the performance and profile of The People, having spent several years on the Daily Mirror in a senior executive role.
"Both Richard and Tina leave with our best wishes for the future and our thanks for the extremely valuable contribution they have made to the Daily Mirror and Sunday Mirror during their tenure as respective editors."
The company plans to appoint a weekday and a weekend editor to work under Mr Embley and said it will launch new e-editions of its papers for tablet computers.
Mr Wallace was the Sunday Mirror's deputy editor until taking the top job at the Daily Mirror in 2004, having worked as a showbiz reporter at the paper previously.
He replaced Piers Morgan at the helm of the daily tabloid when Mr Morgan was dismissed after publishing photographs - later shown to be fakes - which purported to show British soldiers abusing Iraqi prisoners.
Ms Weaver became editor at the Sunday Mirror in 2001 after working her way up as a reporter on the now defunct Today and the Daily Mirror.