Police have arrested Rebekah Brooks, the former chief executive of News Corps' British newspaper arm News International, sources familiar with the situation said on Sunday.

Brooks, 43, resigned on Friday over phone hacking allegations at News International's News of the World newspaper, of which she was once editor. She had been due to appear before a parliamentary committee on Tuesday.

Following are reactions to the news:

PROFESSOR MARTIN INNES, CARDIFF UNIVERSITY, CRIMINOLOGIST

I'm speculating but the reason for the arrest would be that the police would have wanted to take control quite quickly. They didn't want to be bounced into action by anything that come out of the committee inquiry.

It narrows down the options, I should think, for the committee if it's a live investigation, but you have to ask yourself what is more important. The politicians have been for the police to take it seriously and a criminal investigation is probably more important.

This arrest is a significant move. What we can see is that the story is traveling up the food chain.

ADRIAN SANDERS, LIB DEM MP, WHO SITS ON PARLIAMENT MEDIA

COMMITTEE:

I think most people will be aghast that somebody is able to make an arrangement for when they are going to be arrested...For it to happen on a Sunday when the police will probably be on a skeleton staff and the kind of people that would be involved in such questions are likely not to be working on a Sunday. In whose interest was it for this arrest to take place before Tuesday because if it does impede what we are able to ask then that is not going to go down very well I think will my fellow committee members.

The allegations in 2003 that police were being paid as far as I'm aware never led to an arrest of Rebekah Wade as she was. So quite why now just a few hours before our select committee meets an arrangement has been made for an arrest, a lot of people are going to think this is very, very odd.

If this is designed to take the spotlight off the police, at the same time as in a sense giving a shield to Rebekah Brooks, that's a very serious matter indeed. We don't know how much this is actually going to impede our questioning until we've been able to sit down and talk it through with parliamentary counsel.

BOB SATCHWELL, DIRECTOR OF SOCIETY OF EDITORS

I think it was entirely expected and I think that perhaps it might be a good idea for people not to get too excited about each individual chess move in this story, and eventually the truth will come out.

The investigation needs to go on and I hope it goes on very quickly because obviously there is a stain across the whole of journalism in this country, which I believe is totally unwarranted.

BEN PAGE, HEAD OF POLLSTER IPSOS MORI

She hasn't been convicted yet and she wasn't actually working for David Cameron. None of it's good for Cameron, but so far, this doesn't mean he's not going to win the next general election yet.

Because Andy Coulson and Brooks were from the same newspaper group, it would be different than if Cameron had dodgy friends all over the place being locked up .... Cameron did also, remember, call for her resignation last week.

HACKED OFF, GROUP REPRESENTING VICTIMS OF HACKING

The arrest of Rebekah Brooks is a further indication of the scale of the scandal, which our members and many hacking victims have been aware of for some time, but beyond that we can only say that it is a matter for the police.

Hacked Off remains focused on pressing for the right terms of reference for the public inquiry with a view to ensuring that so far as possible the truth of this affair is put before the public.

LAWMAKER CHRIS BRYANT, PROMINENT PARLIAMENTARY CAMPAIGNER

AGAINST MEDIA ABUSES

It looks as if the Metropolitan Police are doing the thorough investigation that they should have done five years ago.

Clearly, Rebekah Brooks has got serious questions to answer. I hope this is not just a means of avoiding answering questions at the select committee on Tuesday.

The waters are very definitely lapping around the Murdochs' own ankles. And it's interesting to note that (British Prime Minister) David Cameron's closest friends, Andy Coulson and Rebekah Brooks, have been arrested. It makes you question his character.

MARK LEWIS, LAWYER FOR FAMILY OF MURDERED SCHOOLGIRL MILLY

DOWLER

Whilst I welcome the widening of the investigation into all those who were employed at the newspaper at the relevant time, this move might have obvious ramifications as regards her willingness to answer question at Tuesday's select committee hearing.

TIM BALE, PROFESSOR OF POLITICS, UNIVERSITY OF SUSSEX

I think this was pretty uncomfortable for Cameron already and it will get more uncomfortable now over the next week. It brings the whole thing closer to him. If one believes all the talk of a 'Chipping Norton' set, it reinforces this impression of a cozy elite at the top of the media/political complex.

Regarding Brooks' appearance before parliament, he said:

I'm not sure she can appear now. I would have thought it difficult for MPs to ask questions or for her to answer without prejudicing any criminal proceedings down the line.

I can't think of any precedents for anybody being invited to appear who is already under suspicion.

(Reporting by Mohammed Abbas and Keith Weir; Editing by Elizabeth Fullerton)