Japan may freeze economic aid to India to protest three nuclear tests conducted Monday, Foreign Minister Keizo Obuchi suggested Tuesday.

Prime Minister Ryutaro Hashimoto told reporters that India's nuclear tests are "very regrettable" and that Japan will abide by the principles stated in its official development assistance policy.

The principles call for taking into account military spending, possession of weapons of mass destruction and the recipient nation's arms exports, among other things, before any aid is supplied.

Obuchi told Indian Ambassador to Japan Siddharth Singh that the Japanese government has no alternative but to take measures in connection with Japan's ODA to India, according to Foreign Ministry officials.

Japan was the largest aid donor to India in 1995, when its assistance accounted for 48 percent of the total aid that India received, the officials said. In 1996, Japan pledged 130 billion yen in loans and 3.4 billion yen in grants to India, the officials said.

Obuchi told Singh that he is concerned the nuclear tests may hamper regional security and that such tests run counter to an international trend toward nuclear disarmament, the officials said.

Singh handed Obuchi a letter addressed to Hashimoto from Prime Minister Atal Bihari Vajpayee, who explained the background for the nuclear tests.

Singh told Obuchi that the regional security situation has worsened as neighboring countries to the west and north have improved their weapons systems, according to the officials.

Singh named Pakistan as the neighboring country to the west but did not specify the country to the north. India shares its northern border with Nepal and China.