Two oil tankers have been evacuated in the Gulf of Oman following reported attacks on the vessels which prompted international alarm and sent oil prices spiralling upwards.

Scores of crew members from the Marshall Islands-flagged Front Altair and the Panama-flagged Kokuka Courageous abandoned the ships on Thursday after sending out distress calls amid explosions on board.

The cause of the blasts was unclear, but one operator said it suspected its ship had been hit by a torpedo.

Iran’s Islamic Republic News Agency (IRNA) reported that Iranian search and rescue teams picked up 44 sailors – 21 from the Kokuka Courageous and 23 from the Front Altair – following the incidents and took them to the nearby port of Jask.

The US Navy’s Bahrain-based Fifth Fleet said it also assisted the tankers after receiving two distress calls.

A statement by the Kokuka Courageous’s management company, BSM Ship Management (Singapore), said 21 crew members of the vessel abandoned the ship after an incident on board which resulted in damage to its hull’s starboard side. The vessel was about 70 nautical miles (nearly 130km) from Fujairah in the United Arab Emirate (UAE) and about 14 nautical miles (26km) from the coast of Iran.

“The Kokuka Courageous remains in the area and is not in any danger of sinking. The cargo of methanol is intact,” the statement said. One crew member was injured during the incident and was receiving medical treatment on another vessel nearby, it added.

The Marshall Islands-flagged Front Altair was carrying 75,000 tonnes of naphtha, a flammable petrochemical feedstock [File: Artjom Lofitski]

Front Altair, meanwhile, had been chartered by Taiwan’s state oil refiner CBC Corp and was carrying 75,000 tonnes of naphtha, a petrochemical feedstock, when it was “suspected of being hit by a torpedo” around noon Taiwan time (04:00GMT), Wu I-Fang, CPC’s petrochemical business division CEO, told the Reuters news agency. He said all crew members had been rescued.

Norway‘s Frontline shipping company, which owns the Front Altair, said its vessel was on fire.

Oil prices surge

Thursday’s incidents, which took place a month after four other tankers were damaged in the same region, spurred a surge in Brent crude oil prices and sent the commodity rising by more than three percent to about $62 a barrel.

The Gulf of Oman lies at the entrance to the Strait of Hormuz. A fifth of the world’s oil consumption passes through the major strategic waterway.

Paolo d’Amico, chairman of the International Association of Independent Tanker Owners (INTERTANKO), said he was concerned about further disruption in the area, warning the “supply to the entire Western world could be at risk”.

“I am extremely worried about the safety of our crews going through the Strait of Hormuz,” d’Amico said in a statement.

Iranian Foreign Minister Mohammad Javad Zarif meanwhile described the incidents as “suspicious”, with the reported attacks coinciding with a meeting between Japanese Prime Minister Shinzo Abe and Iran’s Supreme Leader Ayatollah Ali Khamenei.

Abe was Trhran as part of efforts to help ease rising tensions between the Islamic Republic and the US.

Meanwhile, Japan’s Economy, Trade and Industry Minister Hiroshige Seko told reporters: “A tanker carrying Japan-related goods was attacked. There were no injuries among the crew members. They got off the tanker. There were no Japanese members.”

Other international powers also voiced concern over the incidents, including France and Britain, with the former calling on all parties in the Gulf to de-escalate tensions and keep navigation routes free.

Frictions have escalated in the region in recent weeks, including over an earlier attack on oil tankers off the coast of the UAE last month.

US National Security Advisor John Bolton  Iran was likely behind the May 12 incidents, without offering evidence.

The UAE, meanwhile, claimed the preliminary findings of a probe into it revealed they were part of a “coordinated” operation likely carried out by a state actor, but stopped short of pinning the blame on any specific country.

Iran has denied being involved in the incidents in May.