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.
