Some 14,400 News Corp emails have been published by an Australian newspaper as a storm grows around Rupert Murdoch's company and a former unit's alleged involvement in hacking the smart codes of pay TV rival ONdigital.

The email cache, published online by the Australian Financial Review, could cause issues for Cisco, the networking company that bought NDS, once a News Corp subsidiary, for £3.2 billion two weeks ago.

Allegations have been raised that NDS security head Ray Adams - a former commander in the Metropolitan Police - paid a hacker to access the smart codes of ONdigital, an ITV-owned rival that later collapsed after mass counterfeiting of TV access cards. The messages, purportedly from an NDS unit hard drive, apparently show the unit discussing a pay-TV rival being "totally hacked" by pirates.

The emails also raise questions on News Corp's disputes with pay TV rivals in other geographical areas, including the US and Australasia, it has been reported. The newspaper claimed that NDS's activities in Australia in 1999 caused huge financial damage to News Corp's competitors there.

NDS has not commented. News Corp, its former parent before the Cisco acquisition, said it was "proud to have worked with NDS, whose industry-leading technology has transformed TV viewing for millions of people across the world, and to have supported them in their aggressive fight against piracy and copyright infringement".

In one email, NDS employees appear to discuss the fact that a European pay-TV company was "totally hacked", at a time that News Corp was interested in buying a stake in that company, the FT noted. The email sender writes whether NDS should "start to protect" the encryption method used by the company "while leaving the main...platform compromised", given News Corp's buying interest.

NDS said after a BBC Panorama expose on Monday that it has always operated legally. It added: "These allegations were the subject of a long-running court case in the United States. This concluded with NDS being totally vindicated and its accuser having to pay almost $19m in costs - a point that the BBC neglected to include."

Adams has denied handling encryption codes.

In a statement, Cisco said: "The allegations made by the BBC's Panorama predate Cisco's involvement with NDS by more than 10 years. Given that we remain separate companies, it would be inappropriate for Cisco to comment further." The acquisition is set to close later this year.