On Thursday, US Secretary of State Mike Pompeo said US officials believed that the Islamic Republic of Iran was to blame for the explosions of oil tankers in the Strait of Hormuz. Pompeo said the attacks were part of a campaign of "escalating tension" being carried out by Iran.

The secretary of state said the accusation was based on intelligence assessments and the type of weaponry reportedly involved. He warned that the US would defend its forces, interests and allies in the region. Pompeo provided no evidence or further detail and did not take questions from reporters.

The US military released a video that officials said showed Iran's Revolutionary Guard removing an unexploded mine from the side of one of the two oil tankers, as well as a photograph showing the apparent mine before its removal.

In a statement, Iranian officials said the country "categorically rejects the US unfounded claim" that it is responsible for attacks on two oil tankers in the Gulf of Oman and called on Washington and US allies to "stop warmongering."

"It is ironic that the US, who unlawfully withdrew from the Joint Comprehensive Plan of Action, now calls Iran to come back to negotiations and diplomacy," Tehran's mission to the UN said in a statement. "The US economic war and terrorism against the Iranian people as well as its massive military presence in the region have been and continue to be the main sources of insecurity and instability in the wider Persian Gulf region."

Read more: Iran complies with nuclear deal limits, UN watchdog says

International condemnation

Earlier on Thursday, UN Secretary-General Antonio Guterres said the world could not afford "a major confrontation in the Gulf region."

"I strongly condemn any attack against civilian vessels. Facts must be established and responsibilities clarified," he told a meeting of the UN Security Council on cooperation between the United Nations and the League of Arab States.

The tankers were damaged south of the Strait of Hormuz, a maritime conduit between Oman and Iran that carries almost a fifth of the world's oil exports — from Saudi Arabia, Iran, the United Arab Emirates (UAE), Kuwait and Iraq.

The United States 5th Fleet based in Bahrain said: "US naval forces in the region received two separate distress calls at 6:12 a.m. local time and a second one at 7:00 a.m."

Iran said its navy had rescued 44 crew members from the two vessels.

Norwegian- and Japanese-owned tankers

One of the ships involved was the Front Altair, a Norwegian-owned tanker that was being chartered by Taiwan's state-owned CPC Corp.

The ship bound for Taiwan was carrying 75,000 tons of naphtha, a petrochemical feedstock. It was hit by three explosions, according to the Norwegian Maritime Authority.

Read more: John Bolton says Iran is 'almost certainly' behind oil tanker 'attacks'

Singapore's BSM Management said in a statement that its Kokuka Courageous tanker had been damaged in an unspecified "security incident" while it was transporting methanol to Singapore. Japanese company Kokuka Sangyo later said it was the owner of the ship.

Tracking data showed the ships had been loaded in the United Arab Emirates, Saudi Arabia and Qatar.

All 21 crew members abandoned ship and are now on board the US Navy's USS Bainbridge.

Iran calls attack reports 'highly suspicious'

The reported attacks came amid heightened regional tensions following attacks on four ships off the coast of the United Arab Emirates in May near Fujairah, just outside the Strait of Hormuz.

At that time, the United States and Saudi Arabia blamed Iran, which has dismissed their accusations.

Iranian Foreign Minister Mohammad Javad Zarif said Thursday's incidents were suspicious because they occurred while Japanese Prime Minister Shinzo Abe met with Iran's supreme leader.

"Suspicious doesn't begin to describe what likely transpired this morning," Zarif commented in a tweet on Thursday, without elaborating.

Meanwhile, Russia warned against rushing to blame Iran for the attack and using the incident to stoke tensions with Tehran. Several Russian sailors were on board one of the tankers at the time.

Germany calls for de-escalation

German Foreign Minister Heiko Maas said the incidents were worrying and could escalate tensions in the region.

"The news that we have received ... is extremely worrying," Maas said at a press conference.

"An escalation of the situation is dangerous; these are events that could lead to escalation. We need de-escalation and all sides must contribute to that," said Maas, who recently returned from a trip to Iran.

js/sms (AFP, AP, Reuters, dpa)

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