In a statement, Águas e Energia do Porto reported that following the incident, the Maritime Authority raised the red flag at Pastoras beach as a precaution.

Contacted by Lusa, the captain of the port and local commander of the Douro and Leixões Maritime Police, Silva Lampreia, stated that "part of the pollutant discharge managed to escape" the containment barriers and suction devices, so "some" dispersed into the sea.

According to the captain, the tide is moving south, which is why pollutant stains may appear on other beaches south of Porto, that is, on the Vila Nova de Gaia side.

As a precaution, the authorities are raising the red flag, which prohibits swimming, as they are also “unaware of the true impact of these pollutants”.

Swimming and recreational fishing were banned today as a precaution between the cement pier and the mouth of the Douro due to the discharge of polluting materials into the Granja stream caused by the fire at the Nors group.

“A notice was published prohibiting swimming and recreational fishing along the entire stretch, from the cement pier [near the Casa d’Oro restaurant] to the mouth of the Douro River as a precaution”, the captain of the port told journalists today at Largo do Calem, where the water cleaning work is taking place.

The ban covers an area of ​​approximately 2.7 kilometres.