Confidential information about millions of Britons stored on Indian computer systems could be open to cyber attack from terrorists, fraudsters and hostile nations such as China, the Government will admit today.
In a tacit recognition of the potential scale of the problem, Britain and India will announce moves to boost security against international criminals operating online.
David Cameron and his counterpart, Manmohan Singh, will establish a joint force dedicated to fighting against hacking and organising specialist training for police officers. There will be exchanges set up for academics from the two countries to pool expertise on how best to combat the threat.
The British Government says it is particularly keen to work with India on this because significant UK business and personal data is stored within Indian server farms.
Last night Mr Cameron said the reason for the initiative was twofold: "One is, other countries securing their data is effectively helping us secure our data. Secondly, I think this is an area where Britain has some real competitive and technology advantages."
With the size of its middle-class growing all the time, India is expected to become one of the largest online communities by 2015. By then it is estimated that around 300 million people will have online access, up from 137 million today. Many of those, perhaps most, will be accessing the web through smartphones rather than computers.
Mr Cameron was asked whether there were particular countries that represented a threat to Britain and India's cyber security, among them China. But he said the threat came from "all sorts of different places and organisations – a lot of it is criminal".
Mr Cameron arrived in India yesterday, accompanied by 100-strong delegation of British business leaders representing industries as diverse as defence, brewing and banking. During the three-day visit he hopes to announce the completion of deals that will see the creation of 500 new jobs in Britain.
Mr Cameron also moved to tackle a problem that has cast a pall over Anglo-Indian relations by announcing moves to fast-track visas for Indian business people. Industry chiefs have protested that current visa rules are too restrictive – a complaint echoed by the Liberal Democrat Business Secretary Vince Cable, who has said trade links with India are being undermined as a result. Mr Cameron announced the creation of a new "same-day" visa service for Indian executives. At the moment it can take three days or more for work visas to be approved by the UK.
Mr Cameron travels to Delhi today, where in addition to meeting Mr Singh, he will hold talks with Sonia Gandhi, leader of the ruling Congress Party.