An oil spill from a stricken tanker grounded off the coast of Oman has reached the country's mainland beaches, environmental authorities confirmed on Wednesday, raising fears of one of the most serious maritime environmental disasters in recent years. Crude oil from the Caroline Bezengi, a sanctioned vessel that has been leaking since running aground in June, has contaminated up to 40 kilometres of coastline near Ras Madrakah, a settlement on Oman's central coast. Authorities have warned that oil is also expected to reach the southern shores of Masirah Island — located roughly 15 kilometres offshore — within hours, affecting a further 10 to 20 kilometres of coastline.

The Caroline Bezengi, a 247-metre tanker built in 2001, has been disabled near Oman's Al Hallaniyat Islands since June 8, when its crew reported a suspected explosion on board. The cause of the incident has not been established, and no party has claimed responsibility. The vessel had departed the Russian Black Sea port of Novorossiysk in May, reportedly carrying close to one million barrels of crude oil, and was believed to be bound for India. Western governments have identified the ship as part of Russia's so-called shadow fleet — a network of vessels used to transport Russian oil in circumvention of sanctions imposed following Moscow's 2022 invasion of Ukraine. The tanker is currently sanctioned by the European Union, the United Kingdom, Switzerland, Canada and Ukraine, with its owner and operator registered as Shanghai-based companies.

The scale of the spill appears to be significantly larger than official figures initially suggested. Oman's Environment Authority estimated earlier this week that roughly 400 square kilometres had been affected, but satellite imagery analysed by independent experts and reviewed by Reuters suggests the slick may now cover more than 2,000 square kilometres. The affected waters include a marine protected area near the Hallaniyat archipelago, home to sea turtles, coral reefs, and whale populations. Greenpeace has warned of a potential