British Foreign Secretary Margaret Beckett has urged India to help in efforts to tackle climate change.
Mrs Beckett is greeted by her Indian counterpart, Pranab Mukherjee
She made the call at the start of a six-day visit to the country.
It comes just days after a report commissioned by the British government said that rich nations must act now to reduce greenhouse gas emissions.
Mrs Beckett's counterpart, Indian Foreign Minister Pranab Mukherjee, meanwhile stressed the importance of working together to combat terrorism.
"Both our countries have been the victims of terrorism," he said after hosting talks with Mrs Beckett in Delhi.
"We discussed strengthening cooperation in counterterrorism and have agreed to a meeting of our experts in the area of protection of critical national infrastructure such as the mass transit system and other assets."
The BBC's South Asia Correspondent, Damian Grammaticas, says that it is the longest single visit Mrs Beckett has made to any country since she became UK foreign secretary and her climate change call is a sign of a subtle re-ordering of Britain's foreign priorities.
Her visit follows the release earlier this week of the Stern report in London, which said that rapidly developing countries such as China and India must also be part of a global effort to tackle the problem.
Our correspondent says that tackling climate change has now been elevated to one of the key issues on Britain's international agenda.
Mrs Beckett made clear the British view that responsibility for climate change lies with developed countries who she said "have created these problems because of the unsustainability of our growth and development".
It was incumbent on developed nations to take "the lion's share of action," she said, adding that "climate change is a problem that faces all of us, and must be tackled in partnership" with developing nations like India.
She said that all countries had to understand that doing nothing would lead to far higher costs than if action was taken now.
Her visit also underlines the deepening economic and political co-operation between Britain and India.
Mrs Beckett said India had, this year, become the second largest foreign investor in Britain.
And the two nations are taking practical steps to cooperate on counter-terrorism issues.
Both have suffered attacks on mass-transit systems in major cities, with bombings on the London underground and Mumbai's (Bombay) railway network.
"Combating terrorism and tackling climate change can only be done successfully if the international community work together," the British foreign secretary said.
Both nations are also preparing to host sporting competitions that require major security planning, the Olympics and the Commonwealth Games.