Activists on board a flotilla of vessels sailing toward Gaza say the Israeli navy has begun intercepting their vessels as they approach the besieged Palestinian territory.

The Global Sumud Flotilla, with Greta Thunberg, Nelson Mandela’s grandson, Mandla Mandela, and several European lawmakers aboard, consists of nearly 50 boats and 500 activists and is carrying a symbolic amount of humanitarian aid.

It has remained undeterred in its mission to break the Israeli blockade of the coastal strip and reach Palestinians.

Several activists posted videos on social media late Wednesday in which they said Israeli naval vessels were approaching the flotilla and ordering them to turn their engines off.

Israel’s Foreign Minister Gideon Saar called the flotilla a provocation and warned them to stop and transfer their aid through other channels into Gaza. “It is not too late,” he posted on X.

Israel’s government has accused some of the flotilla members of being linked to Hamas, while providing little evidence to support the claim.

Activists have strongly rejected the accusations and said Israel was trying to justify potential attacks on them.

European governments, including Spain and Italy, which had sent their navy ships to escort the flotilla during part of its journey, urged the activists to turn back and avoid confrontation.

But while Italy's Premier Giorgia Meloni said late Tuesday the flotilla's actions risked undermining U.S. President Donald Trump’s recent proposal for resolving the war in Gaza, Spain's prime minister defended them.