Saudi Arabia on Monday said two of its oil tankers were among four vessels subjected to "sabotage attacks" off the coast of the UAE city of Fujairah a day earlier, prompting condemnation from Gulf countries who urged international guarantees of maritime transport safety.
The other two vessels were registered to Norway and the UAE.
The official Saudi Press Agency reported the confirmation of the attack on the two vessels, quoting the Saudi energy minister.
"Two Saudi oil tankers were subjected to a sabotage attack in the exclusive economic zone of the United Arab Emirates, off the coast of the Emirate of Fujairah, while on their way to cross into the Arabian Gulf," SPA quoted Khalid Al Falih as saying.
The UAE's Minister of State for Foreign Affairs, Dr Anwar Gargash, said on Twitter there was an ongoing investigation into the attack and that the UAE had received great support since the news had broken.
"The great back up and support of the UAE following the deliberate sabotage of the four vessels in our territorial waters are based on the country’s [UAE’s] positive stance in supporting peace and stability.
"We have gained our great friendships by our transparency and positions," he wrote.
"The investigation is being processed professionally. Facts will be clear and we will have our own readings and evaluations."
The UAE on Sunday said the sabotage targeted four boats, without elaborating or naming suspects. It came only hours after Iranian and Lebanese media outlets aired false reports of explosions at the nearby port in Fujairah, which bunkers and ships oil.
He said one tanker was en route to the kingdom to be loaded with Saudi crude oil to be sent to the United States.
"Fortunately, the attack didn't lead to any casualties or oil spill; however, it caused significant damage to the structures of the two vessels," the energy minister said.
Brent crude prices rose by $1.15 to $71.77 on Monday as concerns around supply increased.
Trading and shipping sources told Reuters the Saudi vessels were Bahri-owned very large crude carrier (VLCC) tanker Amjad and crude tanker Al Marzoqah. Bahri, the national shipping carrier of Saudi Arabia, did not respond to Reuters request for comment.
A Norwegian-registered product tanker was also damaged in an incident, ship management company Thome Ship Management said.
"The master of MT Andrea Victory reported the crew were unharmed but there was a hole in the hull area of the aft peak tank. The ship is not in any danger of sinking," the company said in a statement.
The other ship was identified as the A Michel, which was registered in Sharjah.
The incident in a key shipping lane prompted wide condemnation and calls to guarantee the security of maritime transport.
Saudi state TV quoted a source in the Saudi foreign ministry as saying the attacks constitute a "dangerous threat to the safety of navigation and affects negatively regional and international security".
The US has issued an alert to maritime traffic over alleged "acts of sabotage" of ships off the coast of the UAE amid heightened regional tensions between American and Iran.
The US Maritime Administration warned shippers early on Monday to exercise caution when travelling past Fujairah. It gave co-ordinates of the reported sabotage, putting it just north of Fujairah.
No one was hurt and Abu Dhabi called on world powers to help keep maritime traffic safe.
Iran's foreign ministry spokesman Abbas Mousavi expressed concern at the event, warning against attempts to undermine the stability of international maritime transport, the IRNA news agency reported.
Mr Mousavi also "warned against plots by ill-wishers" to disrupt regional stability. He said regional states should be vigilant "in the face of any adventurism by foreign elements" without identifying any state by name.
Saudi Arabia's foreign ministry also condemned the attacks in a post on Twitter.
"We condemn the acts of sabotage which targeted commercial and civilian vessels near the territorial waters of the United Arab Emirates," the ministry wrote.
The Bahraini and Kuwait ministries for foreign affairs also both condemned the attack, stressing the need for the international community to bear the responsibility of maritime trade around the world.
Kuwait said the attacks were criminal and reaffirmed its support for the UAE to secure stability and maintain sovereignty.
Lebanon's Prime Minister, Saad Al Hariri, also condemned the operations, saying it was an attack on Arab security.
Secretary General of the GCC Dr Abdullatif bin Rashid Al Zayani also addressed the attack, describing it as "a serious escalation which demonstrates evil intents by those who planned and carried it out, undermining the safety of maritime traffic in the region and threatening the safety and lives of those on board".
Fujairah is the only terminal in the UAE on the Arabian Sea coast, bypassing the Strait of Hormuz, through which most Gulf oil exports pass, and which Iran has repeatedly threatened to close in case of a military confrontation with Washington.
The emirate has an oil terminal and a pipeline that delivers crude oil from Abu Dhabi which sits on the majority of the country's oil reserves.
The Pentagon said on Friday that it was deploying an amphibious assault ship and a Patriot missile battery to the Middle East to bolster an aircraft carrier force sent to counter alleged threats from Iran.
The increasing tension come as Tehran said on Wednesday it had stopped respecting limits on its nuclear activities agreed under a 2015 deal with major powers.
Iran said it was responding to the sweeping unilateral sanctions that Washington has reimposed since it quit the agreement one year ago, which have dealt a severe blow to the Iranian economy.