A senior Scotland Yard counter-terrorism officer rang the News of the World to offer "highly sensitive" inside information about a police inquiry into phone hacking at the newspaper in exchange for a bribe, a court heard yesterday.

Detective Chief Inspector April Casburn, who ran the Met's financial investigations into terrorists, made the offer in an early-morning phone call to the paper days after her employers had launched a new investigation into voicemail interception at the Murdoch-owned tabloid, Southwark Crown Court in south London was told.

The journalist who took the call, Tim Wood, subsequently relayed his version of the conversation in an email to two of the paper's most senior staff: the news editor Ian Edmondson and crime editor Lucy Panton.

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He wrote: "A senior policewoman – no name given – wants to sell information on the phone-hacking inquiry." She had told him that the police were looking at six people, including Andy Coulson, the former NOTW editor, who was then still the Prime Minister's spokesman in Downing Street.

Det Ch Insp Casburn, 53, from Essex, is on trial accused of committing misconduct in public office by engaging in behaviour that would lead to lower trust in the police "without reasonable excuse or justification".

She denies the charge, saying that, while she did make the call – which was confirmed by phone records – she was acting as a whistleblower who wanted to highlight the diverting of resources away from the fight against terrorism to less serious voicemail interception.

She denies that she asked for payment or disclosed any confidential information not already in newspaper reports. Her trial – the first involving the alleged law-breaking at the now-closed NOTW – is expected to last three days.

At the opening yesterday, Mark Bryant-Heron, for the prosecution, outlined how Det Ch Insp Casburn had contacted a readers' hotline for the NOTW at 7.51am on Saturday 11 September 2010.

At the time she was in day-to-day charge of the Met's National Terrorist Financial Information Unit, which had seconded an officer to Operation Varec, the new inquiry into phone hacking established in the wake of a New York Times article alleging widespread wrongdoing at the NOTW, which had been published 10 days earlier.

On 11 September, a day after a top-level briefing about the operation, Det Ch Insp Casburn called the NOTW and spoke to Mr Wood.

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He tapped out a memo which was subsequently unearthed from News International's computers by officers on the Met's corruption inquiry, Operation Elveden.

Phone records showed that the call – which lasted for eight minutes and 37 seconds – had come from Det Ch Insp Casburn's personal mobile phone and the officer was arrested in December 2011.

Mr Bryant-Heron said: "In short, she tried to undermine a highly sensitive and high-profile investigation at the point of its launch. The information was within her knowledge as a result of her position as a Metropolitan Police officer in SO15, the anti-terrorist command.

"The prosecution says that the act of telephoning the NOTW to offer to sell information and the provision of some information during the call was misconduct – it was a gross breach of the trust the police places in a police officer."

Giving evidence, Mr Wood, a long-serving journalist at the NOTW, said he feared the phone call might have been a hoax because hearing from a police officer was "unusual".

While he could not recall all the details of the call, he did remember that the policewoman had vigorously complained that the Labour peer Lord Prescott had been putting pressure on the police to reopen the investigation "and she resented that".

He said: "She went into great detail about telecommunications offences and the great difficulty they [the police] had in terms of whether it was civil or criminal."

Pressed on whether Det Ch Insp Casburn had asked for payment, he said: "She must have asked for money… I wouldn't have put that [in the email] if she hadn't asked or given an indication."

Patrick Gibbs, QC, for the defence, said that Det Ch Insp Casburn had been at a low at the time of the call, having been "professionally and personally bullied for two years".

He added that she had been going through a divorce and seeking to adopt a baby, having been unsuccessful in her attempts to have her own child.

The call had taken place outside in a public place with the sound of traffic in the background, which could have been responsible for the misunderstanding about the request for payment, he said.

Det Ch Insp Casburn is expected to give evidence at the trial today.

Who's who: the cast

Deputy Chief Inspector April Casburn

She was in charge of the National Terrorist Financial Investigation Unit, which seeks to identify the funding of terrorists groups. The unit is part of SO15, the Metropolitan Police's counter-terrorism command. Because SO15's remit covers royal security (at risk from phone hacking), it carried out the inquiries into the News of the World. Det Ch Insp Casburn was not involved in Operation Varec, set up in 2010 to investigate voicemail interception at the paper, but one of her financial experts was seconded to the operation.

Andy Coulson

Deputy editor of the News of the World under Rebekah Brooks, he edited the paper for four years until 2007, when he resigned over the hacking of the Royal Family. That year he became David Cameron's director of communications. He resigned from that post in 2011. He is currently charged with phone-hacking offences, perjury and corruption – all of which he denies.

Ian Edmondson

He was recruited to the NOTW during Mr Coulson's editorship. He left in 2010, before the start of Scotland Yard's phone-hacking inquiry, Operation Weeting,which arrested him in 2011. He is charged with phone-hacking offences, which he denies.

Lucy Panton

The NOTW's crime editor cultivated contacts with senior officers at Scotland Yard, including Assistant Commissioner John Yates, who attended her wedding to a Met officer. She was arrested by Operation Weeting detectives in 2011 but has not been charged.

Tim Wood

A news editor who joined the NOTW in 1997, his job was to man the news desk overnight. He was finishing his shift when he answered Detective Chief Inspector Casburn's phone call.

The evidence: log of the call

From: Tim Wood

To: Ian Edmondson, Lucy Panton

Time: 8.17am, 11 September 2010

"A senior policewoman – no name given – wants to sell inside information on the phone-hacking inquiry. She says John Yates is using counter-terrorism assets... They are looking at six people: [Andy] Coulson, [Sean] Hoare, a woman who she can't remember the name of, and three others... Pressure to conduct the inquiry is coming from Lord Prescott…"