Drone attacks claimed by Iran-aligned Yemeni rebels shut down one of the kingdom's main oil pipelines on Tuesday, further ratcheting up Gulf tensions after the mysterious sabotage of four ships, two of them Saudi tankers, on Sunday.

"The cabinet affirms that these acts of terrorism and sabotage... do not only target the kingdom but also the security of world oil supplies and the global economy," it said after a meeting chaired by King Salman in the Red Sea city of Jeddah on Tuesday evening.

Tuesday's drone strikes hit two pumping stations on the kingdom's east-west pipeline, which can carry five million barrels of crude per day and provides a strategic alternative route for Saudi exports if the shipping lane from the Gulf through the Strait of Hormuz is closed.

Yemen's Huthi rebels claimed responsibility for the strikes and said they were a response to "crimes" committed by Saudi Arabia and its allies during more than four years of war in support of the government.

The Saudi tankers Al-Marzoqah and Amjad suffered "significant damage" in as yet unexplained sabotage attacks in the Sea of Oman off the United Arab Emirates on Sunday, Energy Minister Khalid al-Falih said, but there were no casualties or any oil spill.

- International investigation -

An Emirati official said three Western countries -- the US, France and Norway -- would be part of an investigation into the ship attacks along with the UAE and Saudi Arabia.

The ships -- which also included the Norwegian tanker Andrea Victory and an Emirati vessel -- were docked in the sea off the coast of the emirate of Fujairah, the official added.

Neither Saudi Arabia nor the UAE, both close allies of the United States, have given details on the exact nature of those attacks, which come amid heightened tensions between Washington and Riyadh's arch-rival Tehran.

OPEC giant Saudi Arabia currently pumps around 10 million barrels per day of which around seven million are exported.

At present, most Saudi exports are loaded onto tankers at terminals on the kingdom's Gulf coast and must pass through the Strait of Hormuz.

The Saudi cabinet called for "confronting terrorist entities which carry out such sabotage acts, including the Iran-backed Huthi militias in Yemen".

Iran has repeatedly threatened to close the Strait of Hormuz in case of a military confrontation with the United States.

- 'Imminent' attacks -

On Wednesday, the United States ordered all non-emergency staff to leave its embassy in Baghdad and consulate in Arbil, northern Iraq, after accusing the Islamic republic of planning "imminent" attacks in the region.

The US has already strengthened its military presence in the region, including deploying a number of strategic B-52 bombers in response to alleged Iranian threats.

Also in Iraq, the German and Netherlands armies are suspending their training programmes for soldiers, the two European countries announced Wednesday, with Berlin citing a "generally heightened alert".

Pumping up the rhetoric, Iran's Defence Minister Amir Hatami warned that the United States and its ally Israel would suffer the "bitter taste of defeat".

"The proud nation of Islamic Iran will once again... pass this sensitive period of time with its head held high," Hatami said.

A day after hosting US Secretary of State Mike Pompeo in Russia, President Vladimir Putin said Moscow was sorry to see Iran's nuclear deal falling apart but stressed his country was not a "fire brigade" to "rescue everything".

Earlier Wednesday, Putin's spokesman Dmitry Peskov expressed concern that tensions over Iran escalated despite assurances from Pompeo that Washington was not seeking war.

"So far we notice the continued escalation of tensions around this subject," Peskov said.

"We are saddened to see the decisions taken by the Iranian side," Peskov said, while arguing that Washington has been provoking Tehran.

Iran and the US have engaged in a war of words in recent weeks since Tehran began to roll back commitments set out in its landmark 2015 nuclear deal with world powers.

US President Donald Trump withdrew the United States from the deal last year and has unilaterally reimposed tough sanctions on Iran.

The International Energy Agency said Wednesday that Iranian crude oil output fell in April to 2.6 million barrels per day, the lowest level in over five years.

Shiite-majority Iran rivals Sunni-ruled Saudi Arabia for influence in the Middle East, with the two taking opposing sides in multiple regional conflicts including in Yemen.