Former News of the World editor Rebekah Brooks knew nothing about a contract the newspaper had with private investigator Glenn Mulcaire, she has told the Old Bailey.

Asked by her lawyer Jonathan Laidlaw QC if she knew anything about the contract, worth £92,000 a year, the former News International chief executive said: "No, not at all."

Ms Brooks admitted that, as editor, an expense as big as that should have been run past her for approval.

The court has heard it is claimed that the contract was organised by former news editor Greg Miskiw, who has pleaded guilty to conspiring to hack phones.

Yesterday, as she went into the witness box for the first time, Ms Brooks denied knowing about Mulcaire, who has also pleaded guilty to phone hacking, and said his activities were not drawn to her attention during her time as editor of the News of the World between 2000 and 2003.

Mr Laidlaw asked the 45-year-old today: "If someone, say Greg Miskiw, was planning to pay £92,000 a year to someone, or a company, should that have been something brought to your attention?"

She replied: "Yes."

Ms Brooks said that, in 2000 and 2001, her "sign-off level" for payments was around £50,000, so any authorisation for something bigger than that should not only have come to her, but would have had to go above her to then-managing editor Stuart Kuttner.

"Anything over £50,000 would go again to the managing director or to the CFO (chief finance officer)," she said.

Mr Laidlaw asked her: "Was that arrangement that Miskiw had come to with Mulcaire drawn to your attention?"

Ms Brooks replied: "No, it wasn't."

The court heard that when Brooks became editor of the now-defunct Sunday tabloid in May 2000, the editorial budget allocated for the year 1 July 2000 to 30 June 2001 was around £23.4m, with a forecast annual revenue of around £160m and profit of around £30m.

Ms Brooks told the court: "The NotW was very profitable during my editorship but then it was a good time for newspapers back then.

"I think every year that I was there we had a healthy profit and I think it stayed around the time."

Ms Brooks, of Churchill, Oxfordshire, denies conspiring to hack phones, conspiring to commit misconduct in public office, and conspiring to cover up evidence to pervert the course of justice.