The publisher of the News of the World has admitted for the first time that four of its journalists personally hacked phones using information supplied by the private detective Glenn Mulcaire.

Until now, the only reporter to have admitted hacking was Clive Goodman, the former royal editor who was jailed in 2007.

But court papers released to The Daily Telegraph show that News Group Newspapers accepts that three other unnamed reporters at the now-defunct tabloid “intercepted voicemail messages using information provided by” Mulcaire.

The document appears to undermine a statement issued by NGN when it apologised to 37 hacking victims last month, in which it stressed that the company was making “no admission as part of these settlements that directors or senior employees knew about the wrongdoing” at the time it happened.

One of the four guilty parties, named only as Journalist B, is described in the court papers as Mulcaire’s “primary point of contact” with NGN between July 2005 and Mulcaire’s arrest in Aug 2006, suggesting the reporter must have occupied a senior position.

NGN also admits that “the services provided by [Mulcaire], including the interception of voicemail messages, were known about amongst a number of employees at the News of the World

Another of the reporters, Journalist E, carried on hacking phones after Mulcaire’s arrest and prosecution, and used their own mobile phone to attempt to access the voicemail of the interior designer Kelly Hoppen as recently as June 2009.

Details of the voicemail interception carried out by the journalists is contained in an “admission of facts” by NGN that would have formed part of a High Court trial if any of the hacking victims had refused to settle their claims.

It was released by Mr Justice Vos, the judge who has presided over more than 50 claims for damages from victims of phone hacking.

Yesterday The Daily Telegraph revealed that the court papers contain fresh evidence of a cover-up by NGN, which formulated an “email deletion policy” in 2009 to “eliminate” potentially incriminating evidence.

Lawyers representing the hacking victims claim in another of the documents that six journalists, identified as Goodman and A, B, C, D and E, personally hacked phones.

Journalist A, described as Mulcaire’s “primary point of contact” until 2005, allegedly told Mulcaire to hack phones on 1,453 occasions.

In total, Mulcaire is alleged to have been commissioned to hack phones at least 2,226 times in five years, an average of more than once a day.

NGN is only prepared to admit that Journalists B, D and E personally hacked phones.

It also admits that on June 22, 2009, a mobile phone belonging to Journalist E was used to call Ms Hoppen’s mobile number twice, and that “the second call generated a voicemail failed access message”. Ms Hoppen is among more than 50 hacking victims to have been paid damages by NGN