Iran did not acknowledge being responsible, but shipping analysts have said it was likely to have been behind the Minoan Pioneer attack on 3 August.

Since the US and Israel began striking Iran at the end of February, data from maritime intelligence company Kpler indicates there have been 67 strikes on vessels in the vicinity of the strait.

Tehran has effectively blockade the waterway, responsible for about a fifth of the world’s oil and natural gas trade. The US has also imposed its own blockade on Iranian ports, which has led to several ships being attacked by US forces.

We have verified several videos shared on social media showing thick, black oil washing up on Suza beach in southern Qeshm. On the other side of the island is the Unesco-designated Hara Biosphere Reserve, home to vital habitats for marine life and migratory birds.

Qeshm, which lies on the northern side of the strait, is a key strategic base for Iran’s military and has been heavily attacked by the US – including a wave of strikes last month which killed three people, according to Iranian state media.

Satellite imagery from 10 August shows the slick visible across an area of more than 300 sq km (116 sq miles) – the size of more than 40,000 football pitches.

“This is what I would call a major oil slick,” said John Amos, CEO of Skytruth, a specialist satellite environmental monitoring group. Based on its size and colour, Amos estimates that the spill is “well over” 100,000 US gallons (380,000 litres) of oil.