DUBAI, United Arab Emirates (AP) — A cargo ship traveling past Yemen in the Gulf of Aden came under attack in unclear circumstances, maritime authorities said Saturday.

The Gulf of Aden is a crucial route for global trade and has seen attacks attributed to Yemen’s Houthi rebels as its civil war rages on. A number of Somali pirate attacks that once plagued the region have mostly stopped in recent years.

The ship ended up off the small port city of Nishtun in Yemen's far east after coming under attack early Saturday morning, according to an alert from the United Kingdom Maritime Trade Organization that is overseen by Britain's Royal Navy.

“Vessel and crew are safe,” the organization said.

No group immediately claimed responsibility for the attack. Yemen's Houthi rebels, who have held the capital, Sanaa, since September 2014, did not respond to requests for comment. Nishtun's port has been used by a Saudi-led coalition battling the Houthis on behalf of Yemen's internationally recognized government.

The British Defense Ministry declined to elaborate on the attack. The U.S. Navy's Bahrain-based 5th Fleet, which patrols Mideast waterways, said it was aware of the incident, but declined to comment further.

Ambrey Intelligence, a British private maritime intelligence firm, identified the vessel attacked as the MV Hasan, a cargo ship flagged out of Sierra Leone that had been on its way to Salalah, Oman.

The Hasan is registered to Oasis Shipping Co., a Marshall Islands-registered firm with an address linking it to a Beirut address for Barhoum Maritime Co. A similarly named company also operates out of Tartous, Syria. An employee at the company in Tartous declined to immediately comment.

The eastern part of Yemen where the ship was attacked is held by the country’s internationally recognized government, amid its yearslong war against the Iranian-backed Houthis. It marked the fourth known attack against shipping in the eastern Gulf of Aden in 2020, according to the private security firm Dryad Global.

“Analysis of previous incident data suggests a number of incidents occurring in the vicinity of the eastern Gulf of Aden that are likely connected to the war in Yemen,” the firm said.

In one incident, the Saudi-led coalition accused the Houthis of using a so-called “drone boat” loaded with explosives to try to attack a ship off Nishtun.

Later Saturday, the U.K. maritime organization reported up to 20 small boats swarmed toward a tanker southeast of Aden. Ambrey said an armed security force on that ship apparently scared off the boats. It wasn't immediately clear who was on those boats.

In late November, a mine in the Red Sea off Saudi Arabia’s coast near Yemen exploded and damaged an oil tanker. Suspicion immediately fell on the Houthis, who have been identified by United Nations experts as using seamines in the conflict.

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Associated Press writers Samy Magdy in Cairo and Albert Aji in Damascus, Syria, contributed to this report.