The 12-person crew, including climate activist Greta Thunberg, is expected to reach Gaza on June 7.

An activist on board the Madleen has issued a 'new alert', claiming that the vessel is being followed by a drone, according to footage shared on social media.

Climate activist Greta Thunberg, 22, is among 12 activists on board the Madleen, hoping to 'break [Israel's] siege on the Gaza Strip' with a delivery of humanitarian aid.