Iran dismissed as “baseless” on Friday US accusations it executed twin attacks that left two tankers ablaze in the Gulf of Oman, raising fears of conflict in the strategically vital waterway.
China called for all sides to resolve the conflict through dialogue as oil prices jumped, while the European Union and the United Nations called for restraint.
Secretary of State Mike Pompeo warned Washington would defend its regional interests after US Central Command blamed Iranian forces for the attacks - the second in a month in the strategic shipping lane.
CENTCOM released grainy black and white video it said showed crew members of an Iranian patrol boat removing an unexploded limpet mine from the hull of Japanese-owned tanker Kokuka Courageous.
No proxy group could be responsible, Pompeo said.
But Foreign Minister Mohammad Javad Zarif tweeted that the US had immediately jumped to make allegations against Iran without a shred of factual or circumstantial evidence.
He accused Washington of seeking to sabotage diplomacy as Japanese Prime Minister Shinzo Abe visited Iran. One of the targeted vessels is owned by a Japanese company while the other was Norwegian-operated.
It is a serious case which threatens our country's peace and stability, Japan's foreign ministry said in a statement, adding that the straits where the incidents occurred were vital for our country's energy security.
With tensions spiralling between Iran and the United States, the European Union called for maximum restraint and UN chief Antonio Guterres warned against a Gulf confrontation.
But Iran labelled the attacks suspicious, as its supreme leader Ayatollah Ali Khamenei rebuffed overtures by Abe to open talks with US President Donald Trump.
Iranian President Hassan Rouhani called the US a serious threat to global stability as he attended an international forum in Kyrgyzstan.
”Over the last two years ... using its economic, financial and military resources (it) has taken an aggressive approach, he said.
The two vessels, which were 10 nautical miles apart en route to Asia, were struck by explosions in the early daylight hours on Thursday after passing through the Strait of Hormuz some 25 nautical miles off Iran's southern coast.
The Front Altair carrying naptha, a refined petroleum product, and owned by the Oslo-listed company Frontline was hit by three explosions, according to Norwegian officials, and remained ablaze into Friday.
Explosions also struck the Japanese-owned Kokuka Courageous, which was loaded with methanol, but the fire on board was soon extinguished. One crew member suffered minor injuries and the ship was on Friday heading towards the UAE port of Khor Fakkan.
There was no claim of responsibility for the blasts, which struck both tankers at the waterline.
Iran said its navy rescued several dozen crew members from the two vessels, while the US Navy said it had picked up 21 from the Kokuka Courageous.
Iran's English-language Press TV aired footage of rescued crewmen from the Norwegian-operated Front Altair, saying they are all in full health.
The crew of the Japanese-owned Kokuka Courageous saw a flying object before a second blast on board, the operator's head said Friday.
The crew members are saying that they were hit by a flying object. They saw it with their own eyes, Yutaka Katada, head of Kokuka Sangyo shipping company, told reporters.
We have received a report saying that something seems to have flew in, there was an explosion and it created a hole in the body of the ship.
Washington has dispatched the destroyer USS Mason to the scene to provide assistance,” CENTCOM said in a statement while Oman said it sent two navy vessels to assist.
Oil prices jumped at the threat of open conflict around the Strait of Hormuz, the chokepoint between the Gulf and the Gulf of Oman, through which some 15 million barrels of crude pass daily.
They spiked by more than four per cent at one stage on Thursday as news of tanker attacks flashed onto traders' screens.
Prices retreated on Friday as as the International Energy Agency downgraded its forecasts for global oil demand growth.