Brooks now faces charges of conspiring to intercept communications and corruption allegations, thought to be related to payments to police.
She was questioned at a London police station where she was arrested by appointment.
A spokesman for Brooks, said she had been told on Friday, after her resignation, that she would be arrested. She had been very surprised to learn that she would be arrested, he said.
In related news, the Metropolitan Police Commissioner Sir Paul Stephenson has resigned.
Police have been accused of accepting money from the defunct News of the World and other newspapers, and of not doing enough to investigate the hacking claims.
Stephenson issued a statement saying he had made the decision “as a consequence of the ongoing speculation and accusations relating to the Met’s links with News International at a senior level and in particular, with relation to Mr Neil Wallis who as you know was arrested as part of Operation Weeting last week.”
Stephenson has been criticised for hiring Wallis, a former News of the World executive editor arrested last week in the scandal, as a part-time PR consultant for a year until September 2010.
He said he had no knowledge of the extent of phone hacking allegations at the tabloid.
We would suspect that police are sitting on enough to at least lay charges. They will want to be seen to be doing something proactive and shift the focus off their own conduct. They may not have enough to get a conviction against Brooks, but will be going on a bit of a fishing expedition to see what comes out of the woodwork.