Violent clashes broke out in London between police and protesters following Israel’s seizure of a Gaza-bound aid flotilla. Demonstrators accused the UK government of failing to pressure Israel to release the flotilla and demanded stronger action.

The Global Sumud Flotilla, which departed from Spain a month ago to challenge Israel’s blockade of Gaza and deliver humanitarian aid, carried more than 400 participants from 44 countries, including Swedish climate activist Greta Thunberg.

The flotilla was intercepted by Israeli forces on Wednesday. Israel’s Foreign Ministry described the mission as a “provocation” that violated what it called a “lawful naval blockade.”

Large protests also took place in Turkey, Spain, Ireland, Italy, Greece, and Tunisia, as demonstrators worldwide condemned Israel’s actions and called for the immediate release of those on board.