Cruise passengers claim they were forced to “wear masks” as a disgusting stench greeted their arrival on Menorca.

The stench in Mahon, the capital of Menorca, was described as “disgusting” and “very intense” and led to a full-scale search for the cause. Menorca is one of the prettiest islands in the Balearics and attracts thousands of cruise tourists.

The Spanish press says the horrible stink was so bad that passengers getting off ships to look round the city had to wear masks.

The matter was immediately reported to the Balearic authorities who brought in four teams of experts to try and find the source.

As yet, it remains a mystery.

Divers were involved in the investigation at the busy port in case there had been a break in the sewage system or a septic tank but this was ruled out when no damage was found.

The port authority says the main theory points to a large vessel stirring up the sludge from the bottom of the harbour.

Locals said it was not just the port which stunk on Wednesday but “all of the island” and suggested bad smells were common on the island.

“Yesterday, all of Menorca smelled, not just the port,” said one resident on social media.

The stench was reportedly present for quite a few hours, eventually disappearing on Thursday.

Experts say Menorca sometimes has an unpleasant smell due to rotting algae or sewage leaks, particularly near popular beaches or tourist resorts. It often has the odour of rotton eggs but generally, the island’s smells are lovely.