NICE, France, June 10, 2025 (BSS/AFP) - French President Emmanuel Macron called on Israel to quickly free activists, including Greta Thunberg, on a boat that was seized Monday as it headed for Gaza in an operation that sparked angry protests in several European cities.

Tens of thousands of people staged rallies after Israel stopped the boat, the Madleen, that was carrying 12 activists.

In France, rallies in Paris and at least five other cities were called by left wing parties. Jean-Luc Melenchon, head of the France Unbowed (LFI) party, called the seizure of the Gaza boat by the Israeli military "international piracy".

In Switzerland, several hundred people blocked train stations in Geneva and Lausanne to protest Israel's military operations in Gaza, media reports said.

Some 300 protesters carrying Palestinian flags occupied two tracks at Geneva's main station for about an hour, leading to delays and cancellations, the reports said. A similar protest was staged in nearby Lausanne where police cleared the tracks.

Macron meanwhile urged the immediate liberation of French nationals among the 12 activists on the vessel.

Macron had "requested that the six French nationals be allowed to return to France as soon as possible," his office said.

France was "vigilant" and "stands by all its nationals when they are in danger," he added. The French government had also called on Israel to ensure the "protection" of the activists. Macron also called the humanitarian blockade of Gaza "a scandal" and a "disgrace".

Israel's foreign ministry said earlier that "all the passengers of the 'selfie yacht' are safe and unharmed", and it expected the activists to return to their home countries.

Israel has virtually sealed off Gaza as part of its military operation in the Palestinian territory since the Hamas militant group's attacks on Israel on October 7, 2023.