News International has ordered the mass deletion of hundreds of thousands of emails from its computer system in the past 18 months, MPs learnt last night.

The news has prompted concerns that vital evidence may have been lost to police and other authorities investigating the phone-hacking scandal. The extent of the deletions was revealed in a letter sent to the Commons Home Affairs Committee by lawyers acting for a technology company, HCL, which manages data for News International (NI).

A shocked Keith Vaz, chairman of the committee, said: "I'm very surprised that so many emails and information appears to have been deleted since the start of this year. This will raise further questions which I'm sure we will want to probe further but it's surprising that such a large number of messages have been deleted. Several thousand emails is a lot of emails." He said staff from HCL may be called to give further evidence before the committee.