ByThomas Copeland, Mark Poynting and Tom Spencer
BBC Verify
An oil spill from a tanker attacked near the Strait of Hormuz is spreading along the United Arab Emirates (UAE) coastline, forcing the closure of some beaches and coastal areas.
Satellite images from Monday show the beginnings of the oil spill from a ship matching the location and dimensions of Gem No.2, which was damaged between 9 and 10 October during a record surge of vessel strikes by Iran.
The slick of oil had spread more than 35km (22 miles) from the tanker by Wednesday, the satellite imagery showed.
UAE authorities said on Thursday that the incident is affecting beaches near the northern city of Umm Al Quwain and verified video from Friday shows the oil washing ashore, colouring the water black.
The UAE's Ministry of Climate Change and Environment said on Thursday that it "immediately began containment" in order to "limit environmental impacts".
Prof Steve Widdicombe, director of Sharjah Marine Science Research Centre in the UAE, told BBC Verify it was "inevitable that there will be an impact", but researchers caution it is too soon to assess extent of the damage.
Initially a much smaller oil leak could be seen emerging from the ship on 19 October.
But the slick appears to have rapidly spread over two days, according to radar satellite imagery reviewed by BBC Verify and intelligence firm MAIAR.
Oil spills can cause immediate deaths of marine animals and other organisms, for example by physically trapping turtles, smothering the feathers of seabirds or damaging the gills of fish.
They can also cause longer-lasting damage, Prof Widdicombe said, if species remain exposed to toxic compounds from the oil which could impact their ability to reproduce.
Researchers have cautioned the environmental impact at this stage is very uncertain, as it depends on factors including the volume and type of oil spilled, how quickly it evaporates or breaks down and the effectiveness of the clean-up operation.
But the spill does extend towards Siniyah and Khor Al Beidah islands, a globally recognised Key Biodiversity Area containing habitats like corals, seagrasses and saltmarshes, as well as species including green turtles and the critically endangered Halavi guitarfish.
The proximity of the spill to this area is the "most concerning environmental angle", according to Eoghan Darbyshire, a scientist at the Conflict and Environment Observatory.
Tanker hit 14 days ago
BBC Verify analysis of the dimensions and location of the ship indicate they match a crude oil tanker called Gem No.2.
Maritime intelligence firm Vanguard reported the Panama-flagged tanker was "struck by an unknown projectile" on 9 October, just north of the town of Al Jazeera Al Hamra, causing a fire on board that was later extinguished.
Verified footage first posted on social media on 10 October showed the crew running across the deck and putting on lifejackets as a large cloud of black smoke rose over the ship.
Iranian state media shared footage of a ship matching Gem No.2 which appeared to show the vessel on fire with burning oil spilling into the sea.
The ship had been attempting to exit the Strait of Hormuz via an "unauthorized and dangerous route", according to state media.
All 22 Indian crew members were rescued, the Indian consulate in Dubai said on 11 October.
Gem No.2 is one of a record number of ships that reported being attacked in and around the Strait of Hormuz at the start of October.
Security experts told BBC Verify this was part of an Iranian effort to assert greater control over the strait, in response to the US military successfully escorting more vessels through the vital shipping lane.
Tankers and other commercial vessels have come under attack from both Iranian and US forces in and around the Strait of Hormuz amid the conflict between the two countries.
Another major oil slick washed up on the shores of Iran's Qeshm Island in August, which experts said threatened wildlife, protected ecosystems and fishing communities.
Additional reporting by Charlotte Green
