Five vessels are said to be circling Freedom flotilla, with the captain instructing the team to stay calm and seated with their passports and lifejackets on, according to a UN special reporter with the group.

Thunberg, a climate campaigner, is among 12 activists aboard the Madleen, which aims to break the blockade of Gaza and deliver humanitarian aid.

Thunberg, a climate campaigner, is among 12 activists aboard the Madleen, which is operated by the Freedom Flotilla Coalition.