The sea captain who rammed a police boat while bringing 40 rescued migrants to an Italian port she'd been warned to stay out of must be freed from house arrest, a judge ruled Tuesday in a decision that angered the Italian government minister who had declared the defiant mariner an outlaw.

Carola Rackete, 31, was arrested after she docked the rescue ship of German nonprofit group Sea-Watch at Italy's tiny Lampedusa island early Saturday, 17 days after taking the migrant passengers aboard off Libya.

Rackete was "doing her duty saving lives," Judge Alessandra Vella concluded in denying prosecutors' request to keep the German captain under house arrest, Italian state broadcaster RAI reported Tuesday night.

Italy's virulently anti-migrant interior minister, Matteo Salvini, banned ships conducting humanitarian rescue missions from Italian waters and ports, contending they boats encourage human trafficking.

Italian port authorities had repeatedly denied Rackete's request to enter the port. After deciding her passengers could remain at sea no longer, she steered into the Lampedusa port without authorization.

Salvini expressed vexation over the court's decision on social media. Speaking on Facebook live, he said it "goes against Italy and the law" and described the Italian people as "good, yes, fools, no."

"Ignoring the law and ramming a motorboat of border police officers aren't enough motives to go to jail," he tweeted with sarcasm.

While depicted by Salvini as a dangerous delinquent, Rackete quickly became the cause celebre in her homeland, Italy and elsewhere in Europe.

Supporters in Italy and Germany pledged over 1.3 million euros ($1.48 million) after a pair of German TV personalities started an online fundraiser for her and for Sea-Watch.

Earlier Tuesday, several impromptu street rallies were held in her support in Italy, including in Palermo, Sicily, and Pescara, a port town on the Adriatic Sea.

Agrigento Prosecutor Luigi Patronaggio said he argued in court that Rackete deliberately rammed Sea-Watch 3 into the much smaller border police motorboat blocking her path to the dock.

He also contended that Rackete should have waited for permission to port since it appeared to investigators the migrants on board were not in a desperate state of need, as the captain had claimed.

But the judge concluded that Italian laws targeting migrant smugglers didn't apply to Rackete case because hers was a "rescue" action, the Italian news agency ANSA said.

"We are relieved our captain is free!" Sea-Watch tweeted Tuesday night. "There were no grounds to keep her arrested, as her only 'wrongdoing' was to enforce human rights on the Mediterranean and to take responsibility where none of the European governments did."

Salvini renewed his resolve to send "the criminal captain Carola Rackete" back to Germany "because (she's) dangerous to national security," ANSA quoted him as saying.

But an immediate expulsion appeared unlikely. Prosecutors in Sicily want to interrogate Rackete on July 9 for a related probe of allegedly abetting illegal immigration.

Rackete's lawyer was not immediately available to comment. The Agrigento courthouse where the judge issued the ruling was closed Tuesday night.

Prosecutor Patronaggio said the judge's denial of his request to keep the captain under house arrest reflected "strong political tensions," ANSA said.

Given the climate on the migration issue in Italy, "whatever decision one takes, there's always the fear to make a mistake," he said.

Briefing lawmakers in Rome earlier, Patronaggio said investigators found no evidence the rescue boats of nonprofit organizations were in cahoots with people smugglers.

In the days before Sea-Watch 3's dramatic docking, Italy allowed 13 migrants to be taken off for medical reasons. On the eve of the disembarking, five European Union countries, including Germany, had agreed to take in the migrants, clearing the way for Italy to authorize its docking.

Sea-Watch said the captain acting in accordance with international law when she forced her way into port in Lampedusa with the rescued migrants on board.

In Germany, Sea-Watch spokesman Ruben Neugebauer said Rackete informed Italian port authorities of her plan to dock after 60 hours after she declared an emergency. He compared the situation to a police vehicle preventing an ambulance from reaching a hospital.