Malta's world-renowned Azure Window rock formation has collapsed into the sea after being hit by heavy stormy weather, an event described as “heartbreaking” by the country’s prime minister.

The limestone arch near Dwejra Bay on Gozo, an island in the Maltese archipelago, is one of the most recognizable landmarks in Europe, known in Malta as Tieqa tad-Dwerja. It has featured in the HBO television series Games of Thrones.

“Reports commissioned over the years indicated that this landmark would be hard hit by unavoidable natural corrosion. That sad day arrived,” Maltese prime minister Joseph Muscat tweeted.

Roger Chessell, a local who was at the scene when the window collapsed Wednesday, told the Times of Malta, “Suddenly, the arch collapsed into the sea with a loud whoomph, throwing up a huge spray. By the time the spray had faded, the stack had gone too.”

The Azure Window has long been a popular attraction for tourists, who were able to take a boat tour that followed the cliffs before spying the grand arch.

In 2013, a three-month geological study concluded that while erosion was inevitable, the structure was not in imminent danger of collapsing.

Last year, the government made walking across the bridge an offence punishable by a fine of about 1,600 US dollars, although enforcement was lacking.