NEW DELHI/ISLAMABAD, 30 May — Britain said yesterday that it did not see war between India and Pakistan inevitable as foreign mediation to defuse tension between the two nuclear-armed rivals gathered momentum. Japan, whose vice foreign minister was in Pakistan, said Islamabad had promised it would step up efforts to curb cross-border infiltration in northern Kashmir state.

British Foreign Secretary Jack Straw described simmering military tensions between the two countries as “dangerous”. “The situation is dangerous, but war is not inevitable. We have to continue with consistent diplomacy,” Straw said as stepped-up artillery clashes between Indian and Pakistani gunners in Kashmir left 20 people dead and 52 injured.

Indian cross-border shelling killed 13 people and wounded at least 22 in Pakistan while seven people, including an Indian soldier, were killed and 30 injured as Pakistani artillery pounded the Poonch region of Indian Kashmir.

Straw told reporters that neither side wished for war. “I am clear that war is not inevitable,” he reiterated before leaving for London, ending his trip to India and Pakistan. The two countries deployed a million troops on their border after Dec. 13, when gunmen attacked the Indian Parliament. India has also expelled Pakistan’s ambassador and cut road, rail and air links with its estranged neighbor.

Before leaving India, Straw briefed Prime Minister Atal Behari Vajpayee on his meetings in Islamabad, officials said, adding that Vajpayee detailed India’s position to the visiting British politician.

Earlier Straw told a news conference that Pakistan President Pervez Musharraf seriously wanted to stop what New Delhi calls “cross-border terrorism” into Indian Kashmir. “I believe that General Musharraf is serious, but the test of everything is action on the ground,” Straw told a joint press conference with his Indian counterpart Jaswant Singh.

But Singh reiterated that India was losing patience with Musharraf, despite his statement this week that infiltration was not taking place. “Gen. Musharraf has had all the time that he wants since Sept. 11,” Singh said. “It is vital that he sees the urgency of the situation.”

In Islamabad, Japanese Senior Vice Foreign Minister Seiken Sugiura said Pakistan had assured him it would step up efforts to curb cross-border infiltration in Kashmir. Sugiura said Pakistani Foreign Minister Abdul Sattar told him: “We will step up efforts to curb movements across the Line of Control”, the de facto border in Kashmir. But despite that glimpse of tentative progress, Australia and New Zealand urged their citizens to leave the subcontinent. Other countries, including the United States, have told their nationals to stay away because of the war fears and anti-foreigner sentiment in Pakistan.