In a statement, the Faro district city hall reported that the results of the bathing water quality analysis collected on Monday "revealed microbiological contamination levels above the reference limit."

After the State Environmental Agency (APA) communicated the information to the municipality at 12 p.m., the ban was declared, with a red flag placed on those beaches. The source of the contamination is still unknown.

"The information was officially communicated to City Hall at noon, which, since then, in conjunction with official entities, has deployed resources to investigate possible sources, still without any evidence, within its jurisdiction," the statement reads.

According to City Hall, given that the source of the possible contamination is still under investigation, the State Health Department has ordered the ban on swimming as a preventative measure until new results are available, it adds.

"Even if no effects were detected, the situation described could pose a health risk to swimmers," it states.

A new analysis has already been conducted, which may lift the restriction if a change in the parameters is recorded, the Algarve municipality also indicates.

"Hoping that water safety and quality can be restored, we regret any inconvenience this situation may have caused".