One crew member was killed and eight others were injured after two UAE oil tankers were struck by Iranian cruise missiles while transiting the southern shipping lane of the Strait of Hormuz, the UAE Ministry of Defence said on Tuesday, in a major escalation of tensions in the strategic waterway.

The ministry said the supertankers — Mombasa and Al Bahiya — were hit by two Iranian cruise missiles in Omani territorial waters along the southern route of the strait, a shipping lane designated by Oman and the United Nations to keep commercial vessels away from Iranian mines and naval activity.

The attack killed an Indian crew member aboard the Mombasa and wounded eight others, including four who sustained serious injuries.

The injured comprised six Indian nationals and two Ukrainian nationals.

Fires broke out on both vessels following the strikes, causing material damage, but authorities said the blazes were later brought under control.

“The Ministry of Defence condemns this brazen attack, which constitutes a serious violation and a clear breach of international law, threatening the security and stability of the region,” the ministry said, adding that the UAE reserves the right to take all necessary measures to protect its sovereignty, security and national interests.

Marine tracking data showed the Mombasa was sailing from Abu Dhabi’s Zirku Island oil terminal to Khor Fakkan in Sharjah when it was attacked.

The route of the Al Bahiya was not immediately available.

Separately, the United Kingdom Maritime Trade Operations (UKMTO) agency reported that the master of a tanker had informed authorities that an unknown projectile struck the vessel’s starboard engine room while it was sailing about 40 nautical miles northeast of Qalhat, Oman.

UKMTO said all crew members aboard that vessel were safe and that authorities were investigating the incident.

It remained unclear whether the report referred to one of the UAE tankers struck in the missile attack.

The latest incident came amid rapidly escalating regional tensions after the US carried out a third consecutive night of air strikes on Iranian military targets, saying the operations were aimed at degrading Tehran’s capabilities in and around the Strait of Hormuz.

The attack also followed Iran’s reported strike on the GFS Galaxy, a Cypriot-flagged vessel managed by a Dubai-based company, over the weekend, further heightening concerns over the security of one of the world’s busiest energy shipping routes.

Oil prices climbed to a four-week high following the latest exchange of hostilities, reflecting growing fears of disruption to global crude supplies through the Strait of Hormuz.