An Iranian government spokesman on Saturday described as a "cowardly attack" an incident that Iranian media have called the apparent targeting by missiles of an Iranian-owned oil tanker, and said Iran would respond after the facts had been studied.
The tanker Sabiti was hit in Red Sea waters off Saudi Arabia on Friday, Iranian media have reported, an incident that could stoke friction in a region rattled by attacks on tankers and oil installations since May.
"Iran is avoiding haste, carefully examining what has happened and probing facts," government spokesman Ali Rabei was quoted as saying by the official news agency IRNA.
Separately, a senior security official said video evidence had provided leads about the incident, adding that the Sabiti was hit by two missiles, the semi-official news agency Fars reported.
"A special committee has been set up to investigate the attack on Sabiti... with two missiles and its report will soon be submitted to the authorities for decision," said Ali Shamkhani, secretary of Iran's top security body, according to Fars.
"Piracy and mischief on international waterways aimed at making commercial shipping insecure will not go unanswered," he said.
Rabei was quoted by IRNA as saying "an appropriate response will be given to the designers of this cowardly attack, but we will wait until all aspects of the plot are clarified".
Saudi Arabia said it received a distress message from the damaged tanker but the vessel kept moving and switched off its transponder before it could provide assistance, the state news agency SPA reported on Saturday.
Leakage of cargo from the tanker has been stopped as it heads for the Gulf, the semi-official news agency Mehr reported. "The tanker is heading for Persian Gulf waters and we hope it will enter Iranian waters safely," it quoted an unnamed official as saying.
Nasrollah Sardashti, head of National Iranian Tanker Company (NITC) that owns the damaged tanker, said the crew were safe and the vessel would reach Iranian waters within 10 days, the Oil Ministry's news agency SHANA reported.
There was no claim of responsibility for the reported incident and it has yet to be independently confirmed.
It was the latest involving oil tankers in the Red Sea and Gulf region, and may ratchet up tensions between Iran and Saudi Arabia, long-time regional adversaries fighting a proxy war in Yemen, which lies at the southern end of the Red Sea.
The United States, embroiled in a dispute with Iran over its nuclear plans, has blamed Iran for attacks on tankers in the Gulf in May and June as well as for strikes on Saudi oil sites in September. Tehran has denied having a role in any of them.
The US Navy's Fifth Fleet, which operates in the region, said it was aware of the reports but had no further information.
The Iranian reports on Friday offered sometimes diverging accounts. State-run television, citing the national oil company, said the tanker was hit by missiles while denying a report they came from Saudi Arabia.
Iran's Foreign Ministry said the ship was hit twice, without saying what struck it. State television broadcast images from the Sabiti's deck saying they were taken after the attack but showing no visible damage. The ship's hull was not in view.
Oil prices rose on the news of the incident and industry sources said it could drive up already high shipping costs.
Political risk consultancy Eurasia Group said it did not have firm evidence about who may have been behind the incident.
"The proximity of the tanker at the time of the attack to Saudi Arabia's Jeddah port might imply that the missiles could possibly have been launched from the kingdom.
"Another plausible theory is that it was an Israeli sabotage operation...The purpose would be to disrupt Iranian tanker activity in the Red Sea corridor as it heads towards the Suez Canal. A third possibility would be that the attack was conducted by a terrorist group," Eurasia said in a statement.
The Red Sea is a major global shipping route for oil and other trade, linking the Indian Ocean with the Mediterranean via the Suez Canal.