Mystery of vital iPhone 'lost' by News International

Rupert Murdoch's News International has failed to recover one of four Apple iPhones issued to company executives and which are now being investigated by Scotland Yard's phone-hacking investigators.

The smartphones, whose existence was only publicly acknowledged by the company this month despite their being given to four senior figures – including the former executive chairman James Murdoch – in the summer of 2009, are the subject of an order from a High Court judge that the phones and their contents, including emails and text messages, must be preserved.

But News International has only managed to locate three of the phones, opening the possibility that emails and, in particular, text messages archived on the missing handset have been lost and cannot be scrutinised. The phones were "heavily used" by the executives, who ran up a bill of nearly £12,000 between them in the 11 months to this May.

The failure of NI to take possession of one of the phones was confirmed at the High Court in London by Hugh Tomlinson QC, the barrister representing victims of phone hacking by the News of the World in civil damages claims. Mr Tomlinson said three of the four phones had been located.

The loss of one of the devices would be embarrassing to Mr Murdoch's News Corp, which has pledged full transparency in the investigations. The existence of the phones was not disclosed to the Leveson Inquiry but NI has insisted the handsets were not "secret".

The company yesterday declined to comment in detail on its investigations into the iPhones. A spokeswoman said: "News International has complied fully with its disclosure obligations." The Labour MP Tom Watson, a leading campaigner on the hacking scandal, said: "In line with News Corp's promise to be transparent on this issue, I call on them to reveal which of the four iPhones that were issued to senior executives in 2009 they appear unable to locate."

Two of the phones, which were on a single contract with O2 rather than NI's normal provider, Vodafone, were issued to Mr Murdoch and Katie Vanneck-Smith, NI's chief marketing officer. Mr Murdoch, who oversaw the phone-hacking settlement with the footballers' union boss Gordon Taylor in 2008 and spearheaded News Corp's ill-fated 2011 bid for BSkyB, specified that he wanted a "white iPhone".

When The Independent called the number of the handset issued to Mr Murdoch it was still active and gave a message asking callers to contact his personal office at NI. But the phones issued to two other executives, including one individual who has since left the company, have been disconnected.

Operation Weeting, the Yard's investigation into phone hacking, is examining call records from the phones.

Text messages and emails sent and received by Murdoch executives and advisers from their BlackBerry devices have provided some of the most revealing evidence heard by the Leveson Inquiry. The period in which the iPhones were in use – and running up bills that reached up to £3,000 per month – covered climactic events for the company, including the closure of the NOTW last July.

NI has strongly denied that the existence of the phones, in particular that of Mr Murdoch, was shrouded in secrecy.

In a separate development, the High Court heard that 20 further civil damage claims are expected to be lodged shortly by phone-hacking victims, taking the total in the latest round of lawsuits to 70.