NEW DELHI, July 9 — India test-fired its longest-range nuclear-capable missile on Sunday for the first time, government officials said. But although the missile was launched, it was unclear whether the entire test was successful, with at least one report saying that the missile had failed at some point in its flight.

The launching has occurred at a time of rising international tension over North Korea's recent missile tests, and as the United States Congress is considering a civilian nuclear pact that the Bush administration negotiated with India.

While the pact does not concern missile tests or other military activity, its critics say the Bush administration failed to obtain any commitment from India to stop producing new nuclear weapons fuel, or to restrict its production of new weapons. The test of the Agni 3 missile (agni means fire in Hindi) appeared intended to show that India's strategic arsenal could reach far beyond Pakistan and cover territory including China.

The missile is reported to have a range of more than 1,800 miles. The Defense Ministry said it had been launched from Wheeler Island, off the coast of Orissa State in the Bay of Bengal, and had taken off successfully.