Not for the first time, Catalonia's tourism authorities have been caught seeking to glamorise their beaches with promotional photographs taken on the other side of the globe.

In the Girona tourist board's latest attempt to spice up its Mediterranean appeal, an image supposedly of the Costa Brava was actually taken on a beach in Perth, Western Australia. The picture shows a man and a boy gazing out to a deep blue horizon of sea and sky, while gentle waves lap the sand beneath their feet. The Catalan version tones down the antipodean brilliance of the original, pastes a Costa Brava logo to the man's T-shirt and adds in Catalan: "Congratulations Costa Brava on 100 years. You really are great."

The photo, taken 9,000 miles from the beach it represents, appeared on the programme of the recent Gastronomic Forum, a prestigious annual jamboree attended by top chefs including Ferran Adria. Some 30,000 copies of the programme were handed to chefs, journalists and the general public during the event.

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The cost of this piece of spin, the food fair's publicity catalogue helpfully revealed, was €3,200 (£2,900). The tourist board, which provided the advert, described it as "a photomontage", but at no time clarified that it did not show the Costa Brava, according to Jaume Von Arend, one of the forum's organisers. "We had no idea it was not the Costa Brava," Mr Von Arend said.

The photo of the Australian beach was provided by Getty Images and forms part of the "Jacobs Stock Photography" collection.

A tourism official said the offending ad was developed by Be Brand, a company specialising in "communication strategy". Girona's tourism board hired Be Brand last November to organise publicity for the centenary celebrations. Spain's rugged north-eastern shoreline was named the "wild coast" by the Catalan poet and politician Ferran Agullo 100 years ago, to launch it as a tourist destination.

The official said "he could not be sure" if Costa Brava tourism authorities knew the photo was of a beach half a world away. Plans for the food fair and the centenary had been in train for two years, but even so "the advertisement was, as always, produced at very short notice," they added.

The embarrassing blunder came as new figures showed the number of overseas visitors to Spain falling by 12 per cent in January from a year ago. And it was not the first such gaffe. Last month, the Catalan tourist board attempted to pass off a photo of a beach in the Bahamas – this time with a young woman strolling across golden Caribbean sand – as a local scene.