The Italian coastguard seized a migrant rescue boat operated by a German aid groups suspected of aiding illegal immigration from Libya, a prosecutor said.
Video showed the Iuventa, run by Jugend Rettet, arriving at the island of Lampedusa surrounded by coastguard vessels after it was stopped at sea.
Police inspected the ship as soon as it docked and checked crew passports. They later took charge of the boat and set sail for a larger port in Sicily.
Jugend Rettet said on Twitter it received no information about the investigation. It could not be reached for further comment.
It was the first time Italian police seized a humanitarian boat. The move came amid growing suspicion over the role non-governmental organisations are playing in picking up migrants off the Libya coast and bringing them to Italian ports.
Ambrogio Cartosio, chief prosecutor in the western Sicilian city of Trapani, told a news conference his investigation into Jugend Rettet was ongoing and no one had yet been charged.
“The evidence is serious,” Cartosio said. “We have evidence of encounters between traffickers, who escorted illegal immigrants to the Iuventa, and members of the boat’s crew.”
Italian media reported the boat had two Syrians aboard who were taken to a refugee centre, but that could not be immediately confirmed.
Cartosio said there was no indication Jugend Rettet received any money from Libya-based traffickers.
“It would be fantasy to say there was a co-ordinated plan between NGOs and Libyan traffickers,” he said.
Cartosio told a parliamentary committee in May he had suspicions about certain humanitarian groups because some rescue crews seemed to know in advance where to locate boats crowded with migrants.
Looking to regulate eight non-governmental groups which regularly rescue migrants in the southern Mediterranean, the Italian government asked them to sign a code of conduct, including a demand to carry an armed policeman aboard their boats.
Jugend Rettet, which describes itself as an organisation of young Europeans, was one of five groups which refused to sign, but Cartosio denied a suggestion there was any link between the refusal and the boat’s seizure.
The 5-Star Movement, which polls say is now the country’s biggest party, accused NGOs of offering a “taxi” service to migrants, while the rightist Northern League party has said all their ships should be impounded.
Humanitarian groups say they are only interested in saving lives, warning thousands of people would die if they were not at sea. Despite their efforts, 2,200 migrants have died so far this year trying to reach Europe from north Africa.
Looking to turn the screws on the traffickers, Italy’s parliament authorised a limited naval mission to help Libya’s coastguard curb migrant flows.
Jugend Rettet says on its website it started patrolling the Mediterranean in July 2016 and rescued 6,526 people in its first year of action.
“We want to put pressure on state actors to enforce the fundamental right to life and security even in the Mediterranean,” the group says.