Theresa May and India's Narendra Modi have discussed boosting trade ties after Brexit as he visited London.
The UK Government said £1 billion in commercial investments had been agreed, which will create or safeguard 5,750 British jobs as ministers announced closer co-operation on trade, technology and defence.
At talks in Downing Street with the Indian prime minister, Mrs May said there had been a "significant increase" in bilateral trade between the two countries over the past year.
Mrs May, who is hoping to secure a free trade agreement with India after Britain leaves the EU, said: "Our trade partnership is showing how we can remove barriers to increase trade between our two countries."
Mr Modi, who is in London for the Commonwealth Heads of Government Meeting, welcomed the UK's decision to join the International Solar Alliance, which he launched in 2016 to promote the growth of solar energy.
"This is a fight not only against global warming, but this is our responsibility towards humanity, towards the next generation.
"I think this is a very important step," he said.
Downing Street said the Prime Minister updated Mr Modi on the Brexit process and "reiterated that the UK will remain committed to global free trade and investment".
A Number 10 spokesman said: "Prime Minister Modi said there would be no dilution in the importance of the UK to India post-Brexit. He said the city of London was of great importance to India for accessing the global markets and would remain so.
"The two leaders said trade between the UK and India had grown strongly over the last year and Prime Minister Modi said that Brexit offers opportunities to further increase trade ties."
The two leaders later visited the Francis Crick Institute, where they met scientists working on cutting-edge research into lung and kidney cancer.