US President Donald Trump blamed Iran on Friday for attacks on two oil tankers at the entrance to the Gulf despite Tehran's denials, stoking fears of a confrontation in the vital oil shipping route.

Iran has dismissed earlier US charges that it was behind Thursday's attacks that crippled two tankers and has previously threatened to block the Strait of Hormuz, through which a fifth of globally consumed oil passes, if its oil exports were halted.

The owner of the Japanese tanker, has meanwhile claimed that the US has provided "false information" about what happened.

"The ship operator said 'flying objects' that may have been bullets were the cause of damage to the vessel, rather than mines used by Iranian forces, as the US has suggested," the Independent reported.

According to the British news outlet, Yutaka Katada, the CEO of the company operating the ship called Kokuka Courageous, said the damage "could not have been caused by mines or torpedos that are shot underwater, since the damage was reportedly above the ship’s waterline".

Russia, on the other hand, warned against jumping to conclusions over the attacks on two oil tankers in the Gulf of Oman.

“We consider it necessary to refrain from hasty conclusions,” the Russian foreign ministry said, calling for a thorough international investigation.

“We strongly condemn the attacks no matter who is behind them,” the ministry said in a statement.

Thursday's blasts followed a similar attacks a month earlier on four tankers, which Washington also blamed on Tehran.

Asked how he planned to address Tehran and prevent any further incidents, Trump told Fox News: “We're going to see.” He also said that any move to close the Strait of Hormuz, through which the world's biggest oil exporter Saudi Arabia and other Gulf producers ship crude, would not last long.

The US military released a video on Thursday it said showed Iran's Revolutionary Guards were behind the blasts that struck the Norwegian-owned Front Altair and the Japanese-owned Kokuka Courageous in the Gulf of Oman, at the mouth of the Gulf.

Iran said it was being used as a “convenient” scapegoat.

Tehran and Washington have both said they have no interest in starting a war. But this has done little to assuage concerns that the two arch foes could stumble into a conflict.

Oil prices surged on Thursday, reflecting the jitters, although they have since given up some of those gains.

U.N. Secretary-General Antonio Guterres told the U.N. Security Council on Thursday the world could not afford “a major confrontation in the Gulf region”.

China, the European Union and others have called for restraint from all sides. Germany said the US video was not enough to apportion blame for Thursday's attack.

The US military said black-and-white footage it filmed from a US aircraft showed Iran's Guards on one of their patrol boats drawing up to the Kokuka Courageous and removing an unexploded limpet mine from its hull.

The Japanese-owned tanker, abandoned by its crew, was being towed to a port in the United Arab Emirates on Friday, after a Dutch firm said it had been appointed to salvage the ships.

The second tanker, the Norwegian-owned Front Altair, which was set ablaze by a blast, was still languishing at sea, although the fire that had charred the hull had been put out.

“Alarming”

Iranian-US tensions ratcheted up after Trump pulled out of a deal last year between Iran and global powers to curb Tehran's nuclear ambitions in exchange for relief from sanctions.

Since then Washington has toughened its sanctions regime, force Iran's oil customers to slash their imports.

Iran's crude exports fell to about 400,000 barrels per day (bpd) in May from 2.5 million bpd in April 2018, starving Iran's economy of its main source of revenues.

Washington has also blamed Iran or its proxies for attacks on May 12 that crippled four oil tankers in the same area. In addition, it has said Tehran was behind May 14 drone strikes on two Saudi oil-pumping stations. Tehran has denied the charges.

“These accusations are alarming,” Iranian Foreign Ministry spokesman Abbas Mousavi said, adding that blaming Iran for Thursday's attacks was “convenient” for US officials.

Tehran has said the United States and its regional allies, such as Saudi Arabia and the United Arab Emirates, were “warmongering” by making accusations against Iran.

The cause of Thursday's blasts remains unclear.

A source has said a magnetic mine could have caused the explosion on Front Altair, which had a cargo of naphtha.

Unwise escalation

Iranian TV showed 23 crew in Iran believed to be from Front Altair on Friday, and said it experts would assess whether they could return to the ship. The crew from Kokuka Courageous were picked up and handed to a US Navy ship on Thursday.

US and European security officials cautioned against jumping to conclusions, leaving open the possibility that Iran's proxies, or someone else, might be behind Thursday's attacks.

Britain said it took the matter “extremely seriously” and, if Iran was involved, “it is a deeply unwise escalation”.

The Trump administration said in May it would send troops and other forces to the Middle East, citing Iranian threats, a move Tehran has called “psychological warfare”.

Pompeo said US policy was to make economic and diplomatic efforts to bring Iran back to negotiations on a broader deal.

Thursday's attack took place while Japanese Prime Minister Shinzo Abe was visiting Tehran with a message from Trump. Japan was a big Iranian oil importer until Trump stepped up sanctions.

But Iran dismissed Trump's overture, details of which were not made public. “I do not see Trump as worthy of any message exchange, and I do not have any reply for him, now or in future,” Iranian Supreme Leader Ali Khamenei said.

In abandoning the nuclear deal, Trump said he wanted Iran to curb its nuclear work and development of missiles, as well as halt support for proxy forces in Iraq, Syria, Lebanon and Yemen.

Analysts said Iran could have carried out the attacks in a bid to gain negotiating leverage.

“There is always the possibility that somebody is trying to blame the Iranians,” said Jon Alterman of Washington's Center for Strategic and International Studies.

“But there is the greater likelihood that this represents an effort to bolster Iranian diplomacy by creating a perceived international urgency to have the United States and Iran talk.”