Iran has categorically rejected claims that the country was behind the attacks on two oil tankers on Thursday, saying they are responsible for maintaining the security of the Strait of Hormuz where the incidents took place.

But the Islamic Republic's version of events is strongly disputed by the US Secretary of State Mike Pompeo, who stated that intelligence pointed towards Iran being behind the attack. The U.S. military released images it said showed Iranian forces removing an unexploded limpet mine from one of the ships.

Iranian foreign minister Mohammad Javad Zarif tweeted that the United States "immediately jumped to make allegations against Iran-w/o a shred of factual or circumstantial evidence."

He said the United States was trying to cover up economic terrorism, referring to sanctions the U.S. re-imposed on Iran.

Meanwhile, Iran has received support from China as President Xi Jinping said that Beijing will keep on developing ties with Iran regardless of how the situation changes.

The incident drove up oil prices and stoked fears of a new confrontation between Iran and the United States.

What happened?

The suspected attacks occurred at dawn Thursday about 40 kilometres (25 miles) off the southern coast of Iran. The Front Altair, loaded with the flammable hydrocarbon mixture naphtha from the United Arab Emirates, radioed for help as it caught fire. A short time later, the Kokuka Courageous, loaded with methanol from Saudi Arabia and Qatar, also called for help.

The U.S. Navy sent a destroyer, the USS Bainbridge, to assist, said Cmdr. Joshua Frey, a 5th Fleet spokesman. He described the ships as being hit in a "reported attack," without elaborating.

The two tankers had been evacuated and the crews are safe.

US secretary of state Mike Pompeo said at a press briefing that the US government's assessment was that "Iran is responsible for the attacks that occurred in the Gulf of Oman today".

Pompeo has directed the US ambassador to the UN to raise the issue before the UN security council.

Zarif had tweeted earlier in the day that it was "suspicious" that the attacks occurred during Japanese Prime Minister Shinzo Abe's visit to Iran.

Tensions between Iran and the UAE and its ally Saudi Arabia have been mounting in the region, epitomised by war in Yemen between forces linked to the two sides.

Euronews Now spoke to Dr Ian Black, Senior Visiting Fellow, Middle East Centre, London School of Economics who described today's incident as "potentially very serious".

"It's the second suspected attack in a month, in the world's busiest shipping lane in terms of oil, against a background of escalating tensions between Iran on the eastern side of the Persian Gulf and the United States, and of course the Arab countries - Saudi Arabia, the Emirates and so on - on the other side of the Gulf," he said.

"So there's a lot of tension there and the attention this is getting, this incident, is precisely a measure of that - the fear that it may escalate into something even more dangerous."

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The suspected attacks

Oil tanker Front Altair was carrying 75,000 tonnes of naphtha, a petrochemical feedstock, when it was "suspected of being hit by a torpedo" around noon Taiwan time (0400GMT), Wu I-Fang, a senior company official for Taiwan's state oil refiner CPC Corp told Reuters.

He said all crew members have been rescued.

The other tanker, the Japanese-operated Kokuka Courageous (operating under a Panama flag), was also damaged in the incident, a spokesman for the vessel's manager BSM Ship Management (Singapore) said.

The spokesman said 21 crew had abandoned ship after the incident, which resulted in damage to the ship's starboard hull. The master and crew were quickly rescued from a lifeboat by the Coastal Ace, a nearby vessel.

Contains modified Copernicus Sentinel data 2019/ Sentinel Hub

Yutaka Katada, the president of tanker operator Kokuka Sangyo, said on Japanese TV that it had heard reports at 6 am local time that "our ship was attacked by a shell".

He added: "The shell hit a section close to the engine. It pierced through the outer panel and it came close to the iron plate of the engine room, creating sparks, which then caused a fire."

According to sources cited by IRNA, Iran's state news agency, Iranian search and rescue teams picked up 44 sailors from the two damaged tankers and took them to the Iranian port of Jask.

The vessels were about 70 nautical miles from Fujairah and about 14 nautical miles off Iran.

Meanwhile, Japan’s Trade Ministry says both tankers were carrying "Japan-related" cargo at the time of the incident.

Iran's response

The incident involving the Japanese-related tankers came as Iran's supreme leader Ali Khamenei met with Japanese Prime Minister Shinzo Abe.

It led to comments from Iranian foreign minister Javad Zarif, who described the incidents as "suspicious" in a tweet.

He wrote: "Suspicious doesn't begin to describe what likely transpired this morning".

Statement from owners

A statement from the owners of the Kokuka Courageous BSM Ship Management (Singapore), said they are launching "a full-scale emergency response following a security incident on board our managed products carrier the Kokuka Courageous in the Gulf of Oman earlier today."

International response

UN Secretary-General Antonio Guterres strongly condemned the attacks against civilian vessels.

The United Kingdom said it was "deeply concerned" by the unfolding incidents in the Gulf of Oman. UK Maritime Trade Operations, part of the Royal Navy, had earlier said it was aware of an incident.

"UK and its partners are currently investigating," the group said without elaborating.

A spokesperson from the UAE's National Media Council told Euronews they do not believe the incident took place within UAE waters.

U.S. Naval forces are assisting tankers in the Gulf of Oman after receiving two distress calls on Thursday, the U.S. Navy's Bahrain-based Fifth Fleet told Reuters.

"We are aware of the reported attack on tankers in the Gulf of Oman. U.S. Naval Forces in the region received two separate distress calls at 6:12 a.m. local time and a second one at 7:00 a.m.," Joshua Frey of the Fifth Fleet said.

Kuwait's Oil Tanker Company said its operations were running smoothly, and had taken precautions to assure it could respond to any emergencies.

Oil prices immediately affected

Oil prices surged by 4% after the report that raises tensions in the Gulf, which have been heightened by a dispute between Iran and the United States.

The area is near the Strait of Hormuz, a major strategic waterway through which a fifth of global oil consumption passes from Middle East producers.

Not the first time

Last month four oil tankers were damaged in the same area after apparently striking objects in the water. The UAE said the incident appeared to have been the result of a sophisticated and co-ordinated action by a state-actor.

Watch more in the player above.