Saudi Arabia on Wednesday displayed drone and missile debris, which it said show oil attacks “unquestionably sponsored by Iran.”
The Saudi government presented the evidence on Wednesday, the BBC reports.
Iran’s foreign ministry had earlier denied any involvement in the attacks on Saudi oil facilities, in an official letter to the U.S.
“Iran has nothing to do with the attack,” states the letter, which was delivered to the U.S. via the Swiss embassy in Tehran.
Switzerland represents Washington’s diplomatic interests in Iran.
“If action is taken against Iran, we will promptly retaliate and the dimensions would not be limited,” Tehran wrote in the letter, according to parts of it published by Iranian news agency IRNA on Wednesday.
The letter was delivered to the Swiss embassy on Monday, according to IRNA.
Tensions in the Middle East have escalated following drone attacks on two major oil facilities in Saudi Arabia.
READ ALSO: Iran denies U.S. claim it was behind oil attack in Saudi Arabia
The pre-dawn attacks on Saturday knocked out more than half of crude output from the world’s top exporter – five per cent of the global oil supply – and cut output by 5.7 million barrels per day.
Yemen’s Houthi rebels, who have been locked in a war with a Saudi-UAE-led coalition since 2015, claimed responsibility for the attacks, warning Saudi Arabia that their targets “will keep expanding”.
But U.S. Secretary of State Mike Pompeo swiftly accused Iran of being behind the assault, without providing any evidence.