A land mine planted by Islamic separatist guerrillas killed at least 33 paramilitary soldiers and their relatives in Kashmir on Sunday, underscoring the urgency of planned negotiations with Pakistan on the future of the disputed Himalayan province.

The soldiers and their families were traveling by convoy on a major highway about 60 miles south of Srinagar, Kashmir's summer capital, when the bus that was taking them on a vacation trip was destroyed by an explosion so powerful that it left a crater six feet deep, according to news reports from the scene.

The attack was the single worst incident of separatist violence in Kashmir since the leaders of India and Pakistan agreed on Jan. 6 to begin formal talks aimed at ending more than half a century of bloodshed and hostility, much of it over the status of the ruggedly beautiful province.

Authorities said the blast killed 18 Border Security Force soldiers, six women, five male relatives and four children. Ten people were wounded. Body parts, bloodstained clothes and lunchboxes were scattered along the pavement, Reuters news service reported from the scene. The soldiers and their families had been traveling from Srinagar to begin a holiday in Jammu, the state's winter capital, according to the Press Trust of India news service.

The violence came just one day after a new government led by India's Congress party was sworn in to replace the ruling coalition of Prime Minister Atal Bihari Vajpayee, whose Hindu nationalist Bharatiya Janata Party was defeated by Congress in parliamentary elections earlier this month.

India's new prime minister, Manmohan Singh, has promised to continue the peace initiative that began under the previous government, but some analysts have questioned whether the mild-mannered economist and former college professor, who lacks Vajpayee's Hindu nationalist credentials, will be able to overcome opposition by some political opponents to any concessions on Kashmir.

As one of his first official acts Sunday, the new prime minister condemned the attack in the state, which is formally known as Jammu and Kashmir, and pledged to work peacefully to resolve India's differences with Pakistan.

"I have learned with the deepest sorrow about the latest cowardly act of terrorists in Jammu and Kashmir," Singh said in a statement. "While we continue to seek peaceful resolutions to all outstanding problems, there can be no compromise on our solemn resolve to deal with the menace of terrorism with firm determination."

Hizb ul-Mujaheddin, one of the major militant groups fighting Indian rule in Kashmir, carried out the attack to avenge the death of its fighters at the hands of Indian security forces, a spokesman for the group told Reuters.

India contends that Kashmir, its only majority Muslim state, is an integral part of the country and cannot be bargained away. Pakistan, which controls part of the province, contends that India grabbed its share of the state illegally when the two countries were carved out in the subcontinent by departing British colonial authorities in 1947.

Under a formula agreed to by the two governments in February, Indian and Pakistani diplomats are tentatively scheduled to meet next month to begin discussing their differences on Kashmir and other points of contention. A meeting between the two sides scheduled for later this week, on nuclear confidence-building measures, was postponed Sunday after Indian officials said Singh needed more time to form his government.

Late Sunday, the government announced that Palaniappan Chidambaram, a Harvard-educated lawyer, will serve as finance minister. From 1996 to 1998, Chidambaram held the same job in a non-Congress government, earning praise from business leaders for slashing tax rates and lowering barriers to foreign investment.

As expected, the government named as its foreign minister Natwar Singh, a former ambassador to Pakistan who served as foreign minister in a previous Congress government. Pranab Mukherjee, another Congress veteran, was named defense minister.