The captain of the migrant rescue vessel Sea-Watch 3 has been questioned by an Italian prosecutor over alleged involvement in illegal immigration.

Carola Rackete was interrogated by the prosecutor's office in Agrigento, Sicily, on Thursday after she docked at a port without authorization.

She was quizzed at the court over allegations of aiding illegal immigration and entering Italian waters without permission.

Speaking outside the court building the German captain urged the European Commission to do everything possible to avoid situations like hers and to accept migrants saved by civilian boats.

She added that she was very happy to have had the opportunity to explain the details of the rescue, which took place on June 12.

Her lawyer Alessandro Gamberini said the interrogation was "simple" and that documentation and logbooks were presented, as well as a declaration on the necessity that forced the captain to enter Lampedusa.

Gamberini added that "it was a normal rescue at sea and totally legal".

He said that the 31-year-old activist is free to leave the country and return to Germany.

Agrigento's prosecutor's office filed an appeal on Wednesday after Judge Alessandra Vella issued a ruling on July 2 not to validate Rackete's arrest and to release her.

Far-right Italian Interior Minister Matteo Salvini introduced a law prohibiting NGO boats to enter territorial waters if they have saved migrants, punishable by a penalty fine up to 50,000 euros, as part of his anti-immigrant policies.

Rackete was arrested on June 28 after entering the port of the island Lampedusa without authorization in order to disembark 40 migrants, who had been on board for 17 days, and after declaring a state of necessity on the ship.

United Nations human rights experts issued a statement on Thursday expressing grave concern over her detention and criminal proceedings in Italy.

“Rescuing migrants in distress at sea is not a crime,” experts said.

“We urge the Italian authorities to immediately stop the criminalisation of search and rescue operations.”

Amnesty International said in a statement on Wednesday: “The baseless charges levelled against this courageous and principled young woman expose the determination of Italian authorities to intimidate and stigmatize people saving lives at sea.” EFE_EPA