'Pinging' – which pinpoints handsets by using mobile phone masts – said to have been carried out on behalf of paper

Senior journalists at the News of the World paid police officers to find celebrities or other people they wanted to write about by tracking their mobile phone signal, it was reported on Tuesday.

The technique, which was know as "pinging" in the paper's newsroom, pinpoints handsets by using mobile phone masts to measure the strength of their signal, according to the New York Times.

Its use normally has to be authorised by the police and security forces with the mobile phone networks on a case-by-case basis under the Regulation of Investigatory Powers Act (Ripa), in which a request signed by a senior police officer is sent to the network authorising the location of the phone.

Using those powers to locate individuals who were not the subject of a police surveillance or serious crime investigation would constitute a breach of Ripa - which was the basis for the jailing of the News of the World's royal editor Clive Goodman in 2007.

The New York Times quoted an anonymous senior Scotland Yard source who said it could have been carried out for the paper by a senior officer, or a more junior officer who persuaded a higher-ranking colleague to carry out the search on their behalf.

He said it would have constituted a "massive breach" of security.

The New York Times said Sean Hoare, a former reporter at the News of the World, had established the location of a contact in Scotland by using the technique.

Hoare said to the Guardian on Tuesday he had obtained the information through Greg Miskiw, a former news editor ahead of a trip to Scotland.

"If you were told to find someone you could go to the news desk, who would give Greg a piece of paper. Greg would sort it. It would cost £300," he said.

Hoare added "Within 15 minutes or half an hour he'd come back and whack it on the table and say: 'There you go'."

He said that he didn't know exactly how the information was obtained by he suspected it was from police officers.

The New York Times quoted another unnamed former News of the World reporter who told it: "I knew it could be done and that it was done."

"Pinging" uses real-time data from cellphone masts to locate phones. Within each mobile network a handful of people with maximum security clearance are allowed to process Ripa requests, which total about 1,000 across the four networks annually, and are audited annually by the interception of communications commissioner's office. Each of the 56 police forces in the UK will have a similarly small number of people authorised to send Ripa requests to the networks – but that means there are around 200 people who could initiate requests. A source at a UK mobile network told the Guardian that it was "unthinkable" that one of their own team could have run a Ripa-style request without being spotted.

Pinging works on any mobile phone that is switched on, and relies on the fact that every few minutes the phone will try to contact mobile cell masts in the vicinity to determine which offers the best connection, to minimise the power needed when placing or receiving a call. A phone can ping a mast up to 35km away; since 2005, many masts have incorporated software that can calculate the approximate direction of the phone. Given the data from two masts, simple trigonometry will give its location to within a few hundred metres.

However real-time pinging requires access to the phone network's data stream, and is generally only used in terrorist cases or serious criminal investigations.

The second NoW reporter told the paper that targets were also tracked by hacking into their credit cards and finding out where they were last used.

The second source said that technique helped the News of the World find Princess Diana's former lover James Hewitt when he left Britain for Spain in the wake of a controversy over a book he wrote about their relationship.

News International declined to comment. Greg Miskiw did not return a call seeking comment.

• This article was amended on 15 July 2011 because the original said Ripa requests are audited annually by the information commissioner.

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