The National Maritime Authority said the alarm was raised at just after 8am, and Maritime Police and a Lifeboat from Olhão were immediately dispatched to the spot to rescue the workers.
“The incident happened immediately after the workers changed shifts, at a time when the sea taxi transporting them was still in the area”, the authority explained.
The workers were thrust into the water and had to be rescued, and back on land were found to be showing signs of hypothermia.
Despite the vessel carrying some 12,000 litres of diesel, the Maritime Authority originally said the incident posed no risk to the environment.
However, it was later found to be leaking fuel, albeit a small quantity, and was surrounded by container barriers brought in from Portimão and Faro as well as Olhão, to limit the spread.
Olhão Port Captain Commandant Nunes Ferreira said up to 300 litres of engine fuel could be released into the water.
However, he explained most of it would evaporate near the vessel; therefore there was no risk of it reaching land.
He also said that “with the current weather conditions, we also don’t believe there will be any risk to the Ria Formosa’s ecosystem.”