Britain is working with the U.S. to ensure a ceasefire between India and Pakistan endures and that "confidence-building measures" and dialogue take place, foreign minister David Lammy said on Saturday.

"We will continue to work with the United States to ensure that we get an enduring ceasefire, to ensure that dialogue is happening and to work through with Pakistan and India how we can get to confidence and confidence-building measures between the two sides," Lammy told Reuters in Pakistan's capital Islamabad at the end of a two-day visit.

The nuclear-armed South Asian arch rivals agreed on May 10 to a ceasefire in their worst fighting in nearly three decades, which followed a deadly attack on tourists that New Delhi blames on Islamabad. Pakistan denies involvement.

Asked about India's suspension of the Indus Water Treaty, potentially squeezing Pakistan's water supply, Lammy said: "We would urge all sides to meet their treaty obligations."

Pakistan has said Britain and other countries, in addition to the United States, played a major role in de-escalating the fighting. Diplomats and analysts say the ceasefire remains fragile.