Greece plans to impose a 20-euro ($22) levy on cruise ship visitors to the islands of Santorini and Mykonos during the peak summer season, in a bid to avert overtourism, Prime Minister Kyriakos Mitsotakis said Sunday.

Greece relies heavily on tourism, the main driver of the country's economy which is still recovering from a decadelong crisis that wiped out a fourth of its output.

But some of its most popular destinations, including Santorini, an idyllic island of quaint villages and pristine beaches with 20,000 permanent residents, risk being ruined by mass tourism.

Speaking at a news conference a day after outlining his main economic policies for 2025, Mitsotakis clarified that excessive tourism was only a problem in a few destinations.

"Greece does not have a structural overtourism problem... Some of its destinations have a significant issue during certain weeks or months of the year, which we need to deal with," he said.

"Cruise shipping has burdened Santorini and Mykonos, and this is why we are proceeding with interventions," he added, announcing the levy.

Greek tourism revenues stood at about 20 billion euros ($22 billion) in 2023 on the back of nearly 31 million tourist arrivals.

In Santorini, protesters have called for curbs on tourism, as in other popular holiday destinations in Europe, including Venice and Barcelona.

Part of the revenues from the cruise shipping tax will be returned to local communities to be invested in infrastructure, Mitsotakis said.

The government also plans to regulate the number of cruise ships that arrive simultaneously at certain destinations, while rules to protect the environment and tackle water shortages must also be imposed on islands, he said.

Greece also wants to increase a tax on short-term rentals and ban new licenses for such rentals in central Athens to increase the housing stock for permanent residents, Mitsotakis said Saturday.

The government will provide more details on some of the measures Monday.