NEW DELHI  Indian authorities have detained a North Korean vessel and are searching it for radioactive material, the first time a ship has been seized and boarded under sanctions adopted by the United Nations Security Council in June.

The cargo ship, M V San, was spotted Friday, officials said, and detained under the authority of the United Nations resolution passed after North Korea tested a nuclear device in May.

The ship anchored without authorization in the Andaman and Nicobar Islands, a territory of India in the Bay of Bengal, last week, according to the Indian military.

Indian officials said it was carrying more than 16,000 tons of sugar bound for the Middle East. But the ship’s proximity to Myanmar, a North Korean ally, and the fact that it had no apparent reason to be in the area raised suspicions.