Everything possible is being done to ensure the safety of Britons caught up in the "horrific" Mumbai terror attacks, Gordon Brown said today.
The Prime Minister said the atrocities in India, which have left at least 100 people dead, including one from the UK, had "shocked and outraged" people throughout the world.
And Opposition leader David Cameron said Britain and India should "stand together and defeat these terrorists".
Mr Brown spoke after visiting staff at a Foreign Office emergency response centre, which took more than 800 calls in its first few hours of operation.
"This is a horrific incident which has shocked and outraged people around the world; this is the loss of innocent lives, people just going about their daily business.
"We've got to do everything we can now to help the Indian authorities," he said.
Speaking before the death of a Briton was confirmed, the PM said: "Our determination is to make sure that those people who are caught up are safe, that those people who are injured are taken care of.
"I have already sent my sympathy and support to Prime Minister Singh of India and said we will do everything we can to help the Indian government.
"Our first duty is towards British citizens who are caught up in this. The High Commissioner has gone from Delhi to visit all those who are injured in hospitals.
"At the same time we are in touch with many people who are caught up in the hotels and given them advice about what they can do.
"Our second responsibility is obviously to root out terrorism and help the Indian government with their action and that is why, at the same time as giving support to the Indian prime minister, we are sending police emergency teams that are well-versed in dealing with terrorism and we will try to give all the support we can through British police and security officials."
He went on: "In time we will assess which group has been responsible - we don't have all the details - and what the implications are for the rest of the world."
Mr Cameron said: "These are absolutely horrific attacks and the pictures on our television screens are dreadful and our sympathy must be with the victims, of course, but also our support for the Indian government at this time.
"And we must stand together absolutely steadfast, saying these terrorists will never win.
"They want to separate countries like Britain and India and we should be saying our trade, our tourism, everything we do together, our relationship together, will get stronger and we will stand together and defeat these terrorists."Reuse content