Britain and India are expected to agree to strengthen co-operation in responding to the threat of cyber attacks by criminal gangs, terrorists and hostile states, as David Cameron meets Prime Minister Manmohan Singh in New Delhi.
Millions of Britons have sensitive personal and financial details stored in "server farms" in India, as a growing number of global companies site data operations on the sub-continent.
And Britain and India share an interest in developing stronger cyber-security defences in response to increasingly audacious attacks on computer networks, believed to stem not only from criminal sources but also state agents in China and elsewhere.
Mr Cameron played down suggestions that the unprecedented UK-Indian co-operation was primarily prompted by shared concern over China, saying only: "Hacking bothers me wherever it comes from."
The PM and Mr Singh are expected to agree a "substantial" strengthening of practical co-operation between British and Indian authorities in the field of cyber security, said Downing Street.
It will be the first time the two leaders have discussed the issue, and is expected to open up opportunities for British security firms in India, which is one of the fastest-developing markets for cyber exports.
The sub-continental giant is expected to become one of the biggest online populations by 2015 with as many as 300 million users.
"I think why we're forging these partnerships with other countries -including trusted partners like India - is twofold," said the PM. "One is that 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. We have put money into cyber security in the Strategic Defence and Security Review in 2010. We have invested heavily in capabilities and understanding of what the threats are and how best to counter them. It is a good competitive advantage we have to offer other countries which want them. India is a case in point."
Asked whether the threat from China outweighed in its seriousness the risk to personal, commercial and official secrets posed by criminals, Mr Cameron replied: "The threat in terms of cyber security comes from all sorts of different places and organisations - a lot of it is criminal. What the British have done is bring together a strategy to help protect key industries, key infrastructure and key capabilities in terms of cyber security and that's work we want to share with others."
On the second day of a three-day visit to India dominated by trade, Mr Cameron will also have talks with President Pranab Mukherjee.