The drone strike that caused an explosion and fire on the Japanese-owned chemical tanker off the Gujarat coast was "fired from Iran," the United States said.

The crew, including 20 Indians, is safe, and the Indian Coast Guard vessel, ICGS Vikram, is on its way to the vessel located 217 nautical miles off the Porbandar coast, the report said, citing the defence officials. ICGS Vikram was patrolling the Indian Exclusive Economic Zone.

The drone strike is seen as a sign of expanding risks to commercial shipping beyond the Red Sea.

The ship was transporting crude oil from Saudi Arabia to Mangaluru.

The attack came amid a flurry of drone and missile strikes by Yemen's Iran-backed Huthi rebels on a Red Sea shipping lane since the start of the Israel-Hamas war on October 7, with the group claiming to act in solidarity with Gaza.

The US military "remains in communication with the vessel as it continues toward a destination in India," the Pentagon said.

The drone strike occurred 200 nautical miles (370 kilometers) off the coast of India, it said, adding that no US Navy vessels were in the vicinity.

It was the first time the Pentagon has openly accused Iran of directly targeting ships since the start of Israel Hamas war, which Iran backs.

This incident follows the recent Indian Navy operation evacuating an injured sailor from the hijacked Malta-flagged cargo vessel MV Ruen in the Arabian Sea.

Coast Guard authorities said that a Dornier maritime surveillance aircraft successfully communicated with the troubled vessel.