ITALY detained an activist-run refugee rescue ship and hit its organisers with a massive fine today after the crew refused to “violate international law.”

Sea-Watch, the German organisation that operates the Sea-Watch 5 rescue ship, announced that its ship had been seized for 15 days and ordered to pay the Italian state €7,500 (£6,493) for refusing to communicate with the Libyan coastguard.

The detention comes after the Sea-Watch 5 saved the lives of 18 people in distress in international waters in the Mediterranean Sea on January 24.

The Italian authorities said the crew had refused to inform the Libyan coastguard of the rescue.

However, Sea-Watch says that shortly before it was carried out, the Libyans attempted to intimidate the ship’s crew in international waters and ordered them to leave, which it does not have the authority to do.

“Such an instruction is unfounded under international law on freedom of navigation. Sea-Watch will take legal action against the detention of its ship Sea-Watch 5,” the organisation said today.

Following an incident last year in which a Libyan ship opened fire on the Ocean Viking, another unarmed activist-run refugee rescue ship, and a spate of other dangerous altercations at sea involving such vessels, 13 civilian search-and-rescue organisations formed the Justice Fleet alliance in opposition to the Italian authorities’ attempt to force them to tell the Libyan coastguard about their rescue operations.

Sea-Watch spokeswoman Giulia Messmer said: “By detaining Sea-Watch 5, the Italian authorities are punishing us simply for complying with international law.

“We do not communicate with Libyan militias that fire on rescue ships and kill people on the move.”