US Secretary of State Condoleezza Rice called on Pakistan on Monday to provide "total" cooperation with India over the Mumbai attacks, at the start of a trip including a "solidarity" visit to New Delhi.
Arriving in London, Rice declined to comment on reports that Pakistan-based Lashkar-e-Taiba -- which is fighting Indian control of disputed Kashmir -- could be behind the deadly attacks which left more than 170 people dead.
"I don't want to jump to any conclusions myself on this, but I do think that this is the time for a complete, absolute, total transparency and cooperation and that is what we expect," she told reporters accompanying her.
"It is extremely important that there would be the highest levels of cooperation between Pakistan and India at this point and that means all institutions."
India's Deputy Home Minister Shakeel Ahmad said Monday that the Mumbai attackers were all from Pakistan -- the strongest such claim since the 60-hour bloodbath which ended Saturday.
Suspicion has fallen in particular on Lashkar-e-Taiba, which was behind a December 2001 attack on the Indian parliament in New Delhi which pushed the neighbours close to war.
"What we are emphasising to the Pakistani government is the need to follow the evidence wherever it leads and to do so in the most committed and firmest possible way," Rice said.
Rice, who will also attend NATO talks in Brussels, was due to meet with British Prime Minister Gordon Brown and Foreign Secretary David Miliband during her stay in London on Monday.
The White House announced Sunday that Rice will travel to New Delhi on Wednesday, as a show of "solidarity with the people of India" following the Mumbai attacks.
"The president has asked me to do that to express our sympathies and our solidarity with the Indian people, and to express our absolute determination to help them in any way that we can to help end this serious threat and bring those who perpetrated this horrible tragedy to justice," Rice said.
"We share the grief and anger of the Indian people. But of course Americans were also killed in this attack and they were killed deliberately because they were Americans and that makes this of special interest and concern to the United States."
The Mumbai attacks saw a group of heavily armed gunmen land in the city by boat, join another cell and proceed to attack a string of targets including a crowded railway station, a hospital, two luxury hotels and a Jewish centre.
Indian external affairs minister Anand Sharma told AFP on Monday that the Mumbai attacks had dealt a "grave setback to the process of normalisation of relations and the confidence-building measures with Pakistan."
Sharma said the Islamist gunmen were "all from Pakistan" and that Islamabad had failed to deliver on its promise to prevent Pakistani soil being used for attacks on India.
India and Pakistan, both armed with nuclear weapons, have fought three wars and nearly came to a fourth over the Indian parliament attack.
Rice played down any sense of crisis of relations between New Delhi and Islamabad.
"They have talked on the phone. This is a different relationship than it was a number of years ago," she said, while acknowledging: "This obviously is a difficult task for this new Pakistani government."
