European countries on Wednesday urged Israel to ensure the safety of their citizens on Gaza-bound aid ships, following its interception of the Global Sumud Flotilla earlier that day.

The flotilla, some 50 vessels with over 500 volunteers from more than 40 countries, aims to challenge Israel's naval blockade and deliver food and medical aid to Palestinians.

The Israeli Foreign Ministry confirmed Wednesday that it "detained several ships from the flotilla," and that the process had been "safe" and the "passengers are being transferred to an Israeli port."

Portuguese authorities confirmed that three citizens, including a member of Parliament, have been detained.

Portuguese President Marcelo Rebelo de Sousa pledged to provide "full consular support" through its embassy in Tel Aviv to ensure their rights and safe return.

Italian Defense Minister Guido Crosetto voiced condemnation "in the strongest manner" as there were also Italian citizens on board. He added that he had authorized the "immediate intervention" of a navy unit, which is heading to the area for possible rescue operations.

France and Spain also expressed concern, urging Israel to ensure the safety of their citizens, guarantee their right to consular protection and allow their prompt return.

Late Wednesday night, the flotilla denounced the "active aggression" of the Israeli military on Telegram, noting that the vessel Florida was "deliberately rammed at sea," while Yulara, Meteque and others were hit with water cannons.

Though all crew members were unharmed, "these illegal attacks against unarmed humanitarian vessels constitute a war crime," it said.