A former editor of the Sunday Mirror was among four people arrested last week as Scotland Yard continues its inquiry into phone hacking.

Tina Weaver, 47, was arrested at her Wandsworth home last Friday as the investigation, called Operation Weeting, widened its net.

Three other current or former Mirror Group journalists were also arrested during the dawn raids, which attracted criticism because Mrs Weaver is pregnant.

It is understood arrests mainly concerned the Sunday Mirror newspaper and officer are focusing on alleged activity between 2003 and 2004.

The four were interviewed at various police stations in London and searches were carried out at a number of addresses.

A spokesman for the Metropolitan Police said: "The four people arrested as part of Operation Weeting this morning have been bailed to return to various London police stations on various dates in April.

"Detectives on Operation Weeting have identified and are investigating a suspected conspiracy to intercept telephone voicemails at Mirror Group Newspapers.

"This conspiracy is being treated as a separate conspiracy to the two being investigated at the now defunct News of the World newspaper."