Image caption Glenn Mulcaire was jailed in 2007 after admitting intercepting voicemails

A man arrested as part of Scotland Yard's inquiry into phone hacking is Glenn Mulcaire, the BBC understands.

He was held on suspicion of conspiracy to hack voicemail messages and perverting the course of justice.

The private investigator was arrested on Wednesday morning and held at a London police station but later bailed.

The Met Police's Operation Weeting is investigating hacking of mobile phone voicemails of public figures by the now-defunct News of the World paper.

The phone-hacking investigation is working its way through about 300 million emails from News International.

Operation Weeting is looking into phone hacking, computer misuse is being investigated by Operation Tuleta and corruption falls under the remit of Operation Elveden.

Mr Mulcaire is the 20th person to be arrested as part of the police's investigations into phone hacking, computer misuse and corruption. He was released on bail to a date in late March pending further investigation, police said.

All but one of the 20 remain under investigation.

Mr Mulcaire was jailed for six months in January 2007 after admitting intercepting voicemails on phones belonging to aides of the Royal Family, including messages left by Prince William.

He was also convicted of intercepting messages of public figures including publicist Max Clifford, Lib Dem MP Simon Hughes and the model, Elle MacPherson.

In July this year, Mr Mulcaire issued a statement through his lawyers apologising to those "hurt and affected" by his actions.

The statement said that having been employed by the News of the World as a private investigator from 2002 he had "acted on the instructions of others".

Last month, in an another statement issued by his lawyer, Mr Mulcaire said he did not delete messages on a mobile phone belonging to the murdered schoolgirl, Milly Dowler and "had no reason to do so".

Earlier, Scotland Yard said a 41-year-old man had been arrested in London in connection with phone hacking and perverting the course of justice.

Former News International chief executive Rebekah Brooks and ex-Downing Street communications chief Andy Coulson are among those who have already been arrested as part of the inquiry.

The scandal has led Met Police Commissioner Sir Paul Stephenson and Assistant Commissioner John Yates to resign, and the NoW to close down after 168 years.

Operation Weeting is now investigating claims of more widespread phone hacking.

Some 1,800 people have come forward to express fears that they may have been hacked.