Large-scale demonstrations have erupted in Sicily after the Italian government approved plans for what would be the world's longest single-span bridge, connecting the island to the mainland.

The project has been discussed for decades and won backing last week from a government committee, with Transport Minister Matteo Salvini hailing it as "the biggest infrastructure project in the West", which is hoped to provide a major economic boost and thousands of new jobs for Italy's impoverished south.

On Saturday, as many as 10,000 people marched in Messina to register their opposition to the 13.5 billion euro ($15.7 billion) project. Construction of the 3-kilometer Strait of Messina Bridge is scheduled to commence next spring and take seven years — fully funded with public money — for completion.

Salvini said the bridge would cut travel across the strait from a ferry journey of up to 100 minutes to a 10-minute drive, surpassing Turkiye's Canakkale Bridge as the world's longest suspension bridge by 1,277 meters — a route he dubbed "a metro over the strait".

However, there is opposition on several grounds, including the environmental effect, forced evictions for construction — which local residents have vowed to resist — the fear of corruption around the awarding of contracts, and the seismic risk in the region.

Prime Minister Giorgia Meloni described the bridge project as "not easy work, but it is an investment in Italy's present and future, a difficult but sensible challenge", adding that it was "a strategic infrastructure for the development of Southern Italy and the entire country".

The project could end up being classified as a piece of defense infrastructure, allowing for quicker deployment of troops to southern areas of NATO — which would help Italy enhance its contribution toward defense expenditure, as is expected of all NATO members. But the fact that this could potentially make it a high-risk security target gives opponents of the bridge another reason to reject it.

"They could offer me three times the value of my house, but that doesn't matter to me," 75-year-old Mariolina De Francesco, whose house stands near the site of one of the bridge's proposed land towers, told The Associated Press.

"What matters is the landscape. They must not touch the Strait of Messina … our lawyers will take action, and we will stop them. That's guaranteed."