A demonstrator holds a placard during a rally in solidarity with Palestinians and to condemn the interception of the Global Sumud Flotilla by Israeli army, in Istanbul, on October 2, 2025. [AFP]

Thousands of people marched through the streets of Barcelona on Thursday to denounce Israel’s interception of a pro-Palestinian aid flotilla bound for Gaza.

Columns of demonstrators, many waving Palestinian flags, converged on the central Plaza de les Drassanes from multiple parts of Spain’s second-largest city.

Protesters chanted slogans including "Gaza, you are not alone," "Boycott Israel," and "Freedom for Palestine."

The Global Sumud Flotilla, with around 45 vessels carrying politicians and activists, departed Barcelona last month to challenge Israel’s blockade of Gaza, where the United Nations reports famine conditions after nearly two years of war.

The Israeli navy intercepted several vessels at sea beginning Wednesday, after warning activists against entering waters it says fall under its blockade.

A boat carrying former Barcelona mayor Ada Colau was among those prevented from proceeding.

Other protests were reported in other Spanish cities Thursday night, including Madrid, Valencia, and Bilbao.

Spain’s Foreign Minister José Manuel Albares said he had summoned Israel’s top diplomatic representative in Madrid to discuss the situation, adding that 65 Spaniards were travelling with the flotilla.

Spain’s public prosecutor’s office said it would collect information on the interception as part of an ongoing probe into alleged Israeli military human rights abuses in Gaza.