The ship’s captain facing jail after defying Italian law to bring 42 migrants into port has said she would do it all over again and hit out at Italy’s far-right deputy prime minister, Matteo Salvini.

“People’s lives matter more than any political game,” Carola Rackete, the German captain of the migrant NGO rescue ship Sea-Watch 3, told the Guardian.

Last week Rackete, 31, was temporarily placed under house arrest for violating an Italian naval blockade that was trying to stop her bringing the group of migrants she had rescued off Libya to the Mediterranean island of Lampedusa.

“Good afternoon, sir. I have to inform you I must enter Italian waters,” she can be heard telling the coastguard after two weeks stranded at sea, in a garbled radio transmission released by her aid group.

“I cannot guarantee the safety of these people any more,” she added. “I have to disembark the 42 people I have onboard. I will turn the ship around and enter Italian waters.”

“Sea-Watch, you are not authorised to enter Italian waters,” the officer replied. “Sea-Watch, do you receive me? You are not authorised to enter Italian waters!”

Facebook Twitter Pinterest Carola Rackete leaves the Sea-Watch 3 in Lampedusa. She was arrested on charges of aiding illegal immigration and attempting to ram a patrol vessel. Photograph: Pasquale Claudio Montana Lampo/EPA

But Rackete, who has worked onboard icebreakers at the north pole, had already made up her mind.

“My arrival time in the port is estimated at around two hours,” Rackete responded. Shortly afterwards she forced her way into the port of Lampedusa, risking ramming a military vessel that was trying to prevent her from docking.

“For two weeks, we had been informing the authorities that the situation of the people onboard was becoming more and more critical and that the medical conditions of migrants were getting worse, day after day,” Rackete told the Guardian. ‘’But it was like talking to a brick wall. The incident at the port was the desperate outcome of a frustrating chain of events that started almost 20 days before.”

On 12 June, Sea-Watch 3 rescued the group of migrants from an inflatable raft drifting off the coast of Libya. Rackete declined to take them to Tripoli, where migrants, according to aid groups and witnesses, risk imprisonment and torture. She instead headed towards Lampedusa.

“A few days after that rescue, the Italian authorities informed us, in the middle of the night, that the government had introduced a new security decree that forbade NGO rescue boats from entering Italian territorial waters,” said Rackete.

Drafted by Salvini, the leading figure in Italy’s far right-populist coalition government, the decree also allows for fines of up to €50,000 (£45,000) and the impounding of boats that bring migrants to Italy without permission – upping the ante after a declaration last year that Italian ports would be closed to lifeboats.

Rackete refused to take no for an answer.

Facebook Twitter Pinterest Sea-Watch 3 and an Italian coastguard boat off Lampedusa on 27 June, the day before Rackete forced her way into port. Photograph: Matteo Guidelli/AP

“We had people suffering from diseases that could not be treated onboard,” she said. “We had people who needed special care. But the thing that started to worry us was their psychological condition.

“There were people suffering from PSTD after the violence suffered in Libya. We had people on board who had a history of attempted suicides. And we could not give these people any hope, like: ‘Hey, hold on, we are coming in three days.’ And this lack of hope made things increasingly desperate and frustrating.”

She decided to enter Italian territorial waters, knowing that she would place herself in legal jeopardy.

“On the following day, after entering Italian waters, I was informed that the Agrigento prosecutors had placed me under investigation for aiding illegal immigration and for having entered territorial waters without permission,” said Rackete. “And you know what? As bizarre as it may seem, we were happy onboard. Because, as had already happened in May, this meant the prosecutors would take responsibility for landing people in order to investigate them.”

But Italy was still refusing to allow the migrants to disembark. As their desperation increased, Rackete ordered more crew members to come up to the ship’s deck.

“We began to fear the migrants might jump in the sea out of desperation,” she said. “A doctor from our team slept on deck to monitor the situation. We were told a political solution was at hand. There were dozens of cities willing to help the migrants. And yet, after days, the solution wasn’t there.

“I assembled the crew and informed them I would enter the port that night. They were worried, because they knew the legal consequences would be serious. But at the same time, they were relieved.”

On the night of 28 June, Rackete forced her way past a military patrol vessel that was going back and forth to try to stop her from docking.

Forty migrants landed that night – two had already been evacuated because of a medical emergency.

The German captain was arrested on arrival, to applause from about 100 people who had arrived on the quay to support her, and insults and threats of rape and murder from others in the crowd.

Facebook Twitter Pinterest Protesters in Amsterdam, part of Europe-wide demonstrations in solidarity with Rackete. Photograph: Ana Fernandez/SOPA Images/Rex/Shutterstock

“I heard someone yelling at me, but I focused on a group from the local Lampedusa community who have always helped migrants and who came there to support me,” she said.

Freed from house arrest, Rackete still faces the prospect of a long trial on the charge of aiding illegal immigration. Salvini is urging the authorities to expel her from Italy because she is considered a “danger to national security”.

“The behaviour from the captain of the pirate ship was criminal,” he has said. “She tried to ram a military patrol boat, putting the lives of the officials at risk. She will go back to Germany where authorities would not have been that tolerant if an Italian captain had made an attempt on the lives of German police officers.”

Rackete said: “Salvini represents a phenomenon, that of the advancement of rightwing parties, which is unfortunately taking place throughout Europe, including Germany and the UK and which speaks of immigration without being supported by facts.

“I hope my gesture will lead to concrete solutions in Europe for migrants. Dozens of cities were willing to host these people, and it is they should be free to do so without national governments hindering them. As for myself, I hope to return to the sea soon, because that is where there is need.”

Rackete was born in Preetz, Schleswig-Holstein, and raised in Hambühren, in Lower Saxony. She has a master’s degree in environmental conservation and speaks five languages. She decided to join Sea-Watch 3, a rescue ship run by the German NGO Sea-Watch, in 2016 because she “was lucky enough to have a nautical licence and there aren’t many people who are willing to do it.

“I don’t have a flat, I don’t have a car, I don’t care about making a regular income and I don’t have a family. There was nothing holding me back from making this commitment.”

With an active investigation and the spectre of a long trial, it is unclear when she will be able to get back in command of a ship.

“I just hope the law changes before then. If it were not so, if I were to find myself in the same situation, I have no doubts I would do everything again.”