An oil spill from a damaged tanker off the United Arab Emirates (UAE) has expanded, prompting authorities to close more beaches and raising concerns over marine life.

Images from the European Union’s Copernicus satellite network, dated October 24, show the spill spreading over recent days towards the coastline of Umm Al Quwain. Dark layers of oil are visible across the sea and along parts of the northern emirate’s coast.

The spill comes amid rising security risks in Gulf shipping lanes following the start of the US-Israeli war with Iran. Attacks on commercial vessels have heightened concerns over the conflict’s environmental impact. October has recorded the highest number of attacks on commercial shipping in the Strait of Hormuz and nearby waters, according to data compiled by the Washington Institute for Near East Policy.

The UAE said on Friday that authorities were working to contain the leak. The Ministry of Climate Change and Environment is also assessing the environmental damage.

Officials have not identified the tanker or confirmed the cause of the spill. However, experts told Reuters that the oil was leaking from the Gem No.2. Shipping sources said the vessel was struck by an unidentified projectile last month, triggering a fire that was later extinguished.

Satellite images from the EU’s Copernicus Sentinel-2 satellites show a large oil slick spreading from the tanker.

Authorities in several northern emirates have restricted access to coastal areas. The UAE environment ministry announced on Friday that all beaches and coastal areas around Umm Al Quwain city would remain temporarily closed. Neighbouring Sharjah also shut Al Hamriyah Beach as a precaution.

"The reported oil spill off Umm Al Quwain is a serious environmental concern. The temporary closure of beaches and coastal areas is a prudent precaution while the extent of the spill and the movement of the oil are assessed," Nidal Hilal, Professor of Engineering and Director of New York University Abu Dhabi's Water Research Centre, told Reuters.

In Ras Al Khaimah, known for its beaches and luxury resorts, authorities announced on Saturday that all beaches would remain closed until further notice.

The International Union for Conservation of Nature (IUCN) says UAE waters support rich marine life, including more than 500 fish species, as well as dolphins, marine turtles, plants and corals.