Oil Tanker Attacked at Saudi Port Amid Iran Tensions

The attack caused a blast and a fire on the Singapore-flagged BW Rhine, according to Hafnia Ltd. , which owns and operates the vessel. The fire was extinguished and all 22 sailors—including nationals from the Philippines, India, China and Romania—were unhurt, the company said. The ship’s hull was damaged in two locations and some oil may have leaked, it added.

It also exposed security vulnerabilities in the kingdom by targeting a vessel while at a Saudi port. The country’s ports are better protected than offshore waters, where most previous attacks have occurred.

A spokesman for the Saudi Energy Ministry called it a terrorist attack, without assigning blame. He said there was no impact on supplies or damage to the unloading facilities in Jeddah, an important Red Sea port for the kingdom.

“These acts of terrorism and vandalism, directed against vital installations, go beyond the kingdom and its vital facilities, to the security and stability of energy supplies to the world and the global economy,” the spokesman said.

Two European officials involved in maritime security in the Red Sea said the attack was likely carried out by the Iran-aligned Houthi rebels in Yemen, who have been battling a Saudi-led military coalition in a six-year civil war.

The Houthis declined requests for comment. But an official from the movement who wasn’t authorized to speak to the media appeared to take responsibility. Saudis “attack Yemenis, so they should expect Yemenis to attack back,” he said.

The coalition didn’t respond to requests for comment. Previous attacks in the strategic waterway have been blamed on or claimed by the Houthi rebels.

Saudi oil infrastructure has come under increasing attack, most notably last year in waters off the kingdom’s eastern coast and at inland sites, which Washington and Riyadh blamed on Iran, despite a claim of responsibility by the Houthis. Tehran denied involvement in those attacks and says it doesn’t control the Houthis.

Saudi Arabia and Iran have struggled for decades in a battle for regional supremacy, each taking opposing sides in violent conflicts across the Middle East. Following years of increased U.S. sanctions after President Trump withdrew from the Iran nuclear accord in 2018, Tehran now also faces further isolation as Washington brokers normalization deals between Israel and Arab countries based largely on mutual enmity towards Iran.

Iran blamed Israel for the killing of its scientist, Mohsen Fakhrizadeh, in November and promised to retaliate, but said it would do so on its own time as Tehran also seeks to keep open a path to diplomatic re-engagement with the incoming Biden administration. Israel has declined to comment on allegations that it was behind the killing, which came after a January U.S. drone strike in Iraq that killed Maj. Gen. Qassem Soleimani, Iran’s most prominent military commander.

Kamran Bokhari, director of analytical development at the Center for Global Policy, a think tank in Washington, said the choice of weapon and target in Monday’s attack as well as the considerable distance from Yemen’s war zone—over 700 miles away—indicated a possible Iranian role, even if Houthi operatives were involved. He said after recent setbacks, Tehran is under pressure to demonstrate to its own people and its proxies across the region that it’s still capable of striking back.

“It’s a subtle, backchannel message to the U.S. It’s demonstrating that the Iranians have power project capabilities not just in the Strait of Hormuz but also on the other side of Saudi Arabia,” said Mr. Bokhari. “If it is them, it’s also sending a message to the Saudis that ‘You’re vulnerable, we can make it very painful for you’…and it’s a message to Israel of Iranian reach.”

The latest escalation also comes as the Houthis accuse the Saudi coalition of exacerbating Yemen’s fuel crisis and inflating gasoline prices by blocking oil shipments.

The Red Sea is a major conduit for oil and other trade flowing from the Middle East to Europe, Asia and North America. About 6.2 million barrels a day of crude and refined petroleum products were shipped through the Bab el-Mandeb strait that separates the Red Sea from the Gulf of Aden in 2018, according to the U.S. Energy Information Administration.

Last month, a Greek-operated oil tanker at the Shuqaiq terminal, south of Jeddah and near the Yemeni border, was damaged in what the Saudi coalition called a foiled terrorist attack by the Houthis.

Two days earlier, the Houthis said they struck a fuel depot operated by Saudi Aramco in Jeddah with a primitive cruise missile. Aramco said the strike, which caused no casualties, tore a hole in an oil tank and triggered an explosion and fire.

The Houthis have previously used remote-controlled dinghies laden with explosives to attack ships in Saudi Arabia’s territorial waters and planted sea mines to disrupt shipping traffic. A Western official in the Gulf said the kingdom’s authorities have noticed an increase in the amount of mines being deployed in the Red Sea in recent months.

The European security officials said Monday’s attack came just days after the coalition intercepted two boats laden with explosives near the Houthi-controlled port of Hodeidah.

The Yemen conflict pits the Saudi-led coalition against the Houthis, who took over the capital, San’a, in 2014. Saudi Arabia and its allies see the Houthis as pawns of Iran, the kingdom’s main regional rival, and accuse the Islamic Republic of supplying the rebels with missiles and other arms. Iran has denied arming the Houthis, but says it supports their cause politically.

United Nations efforts to negotiate a nationwide cease-fire ahead of wider political negotiations to end the war in Yemen have been stalled amid what aid groups call the world’s worst humanitarian catastrophe.

Attacks blamed on the Houthis and Iran have hit the core of the Saudi economy, crystallizing the risks to the region’s oil industry. Missile strikes last year on Aramco’s Khurais oil field and Abqaiq—the world’s largest oil-processing facility—led to the most extensive outage the oil industry has ever seen, knocking out 5.7 million barrels of daily crude-oil production, nearly 6% of global output.

The price of Brent, the international oil benchmark, was about flat up at $50.28 a barrel Monday.

Commodities-data company Kpler said in a note the vessel hit by the explosion on Monday had been chartered by Saudi Aramco and was carrying gasoline from a refinery in the northern city of Yanbu.

Aramco didn’t immediately respond to a request for comment.

The port was closed for an unknown duration, the U.K. Marine Trade Operations, a British Navy center in Dubai that monitors security for commercial vessels in the region, said following the blast. It cited Jeddah’s Maritime and Rescue Coordination Center, where an official declined to comment. The UKMTO said it recommended “extreme caution” to tankers sailing in the area following the incident.

—Benoit Faucon, Sune Engel Rasmussen and Saleh al-Batati in London contributed to this article.

Write to Summer Said at summer.said@wsj.com and Stephen Kalin at stephen.kalin@wsj.com