US President Donald Trump blamed Iran on Friday for attacks on two oil tankers at the entrance to the Gulf despite Tehran's denials, raising 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. It has previously suggested it could block the Strait of Hormuz, the main route out for Middle Eastern oil, if its own exports were halted.
The blasts followed similar attacks a month earlier on four tankers, which Washington also blamed on Tehran.
They come at a time of escalating tension between the two countries. Last month the United States sharply tightened economic sanctions against Iran, which in response has threatened to step up its nuclear activity.
"Iran did do it and you know they did it because you saw the boat," Trump told Fox News.
He was referring to a video released on Thursday by the US military which said it 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 the video proved nothing and that it was being made into a scapegoat. "These accusations are alarming," Foreign Ministry spokesman Abbas Mousavi said.
Iran has accused the United States and its regional allies such as Saudi Arabia and the United Arab Emirates of "warmongering" by making accusations against it.
Asked how he planned to address Tehran and prevent any further incidents, Trump told Fox News: "We're going to see." He also said any move to close the Strait of Hormuz would not last long.
Nevertheless, Trump, who last year pulled the United States out of an agreement between world powers and Tehran to curb Iran's nuclear programme in return for the lifting of sanctions, said that he was open to negotiations with Iran.
Iran has repeatedly said it will not re-enter talks with the United States unless it reverses Trump's decision to withdraw from the nuclear deal.
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 rose about 1 percent on Friday, reflecting the jitters. Insurance costs for ships sailing through the Middle East have jumped by at least 10% after the attacks, ship insurers said.
U.N. Secretary-General Antonio Guterres called on Friday for an independent investigation of the attacks. He told the U.N. Security Council on Thursday the world cannot afford "a major confrontation in the Gulf region."
The tanker attacks took place while Prime Minister Shinzo Abe of Japan - a big buyer of Iranian oil until it was forced by the new US sanctions to stop - was visiting Tehran on a peacemaking mission, bringing a message from Trump.
Iran dismissed Trump's message, 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.
Trump and Abe discussed the oil tanker attacks in a phone call on Friday, the White House said.