Forty-one refugees and migrants disembarked overnight at the port of Lampedusa after a charity vessel that rescued them off Libya defied an attempt by Italy’s far-right interior minister, Matteo Salvini, to close ports to NGO boats.

The Italian-flagged Alex, run by the NGO Mediterranea, was escorted by the Italian coastguard and on Saturday the ship was seized by police, the captain was put under investigation for allegedly aiding illegal immigration, and the rescuees eventually disembarked. Mediterranea was fined €16.000 (£14,300).

The arrival of the Alex, which docked in the Sicilian port after spending two days stranded at sea, follows the arrest of Carola Rackete, the German captain of the another NGO rescue boat, Sea-Watch 3. On 28 June she was temporarily placed under house arrest for violating an Italian naval blockade that was trying to stop her bringing to the Sicilian port a group of asylum seekers she had rescued in the central Mediterranean.

Rackete told the Guardian in an interview on Saturday: “If I were to find myself in the same situation, I have no doubts I would do everything again, because people’s lives matter more than any political game.”

Rackete was arrested on charges of resistance and violence against warships. As she had manoeuvred her vessel into the port, she had risked ramming into a military boat that was trying to prevent her from docking.

On Tuesday a judge in Agrigento, Sicily, released her from the house arrest, ruling that Rackete had been carrying out her duty to protect life and had not committed any act of violence. The judge also ruled that neither Libya nor Tunisia were safe countries for migrants.

Fot this reason, the Alex, which on 5 July rescued a group of people from an inflatable raft drifting off the coast of Libya, decided to head to Lampedusa, “the only possible safe port for landing”, as Mediterranea said in a tweet.

“Law enforcement forces are ready to intervene … in a normal country there would be immediate arrests and the boat would be impounded,” Salvini replied in another tweet. Salvini, who is also deputy prime minister, has repeatedly declared Italian seaports closed to NGO rescue vessels, leaving several boats stranded at sea for weeks.

On 14 June Italy’s far-right-populist coalition government introduced a security decree that forbade NGO rescue boats from entering Italian territorial waters and allowed for fines of up to €50,000 (£45,000) and the impounding of boats that brought migrants to Italy without permission.

However, as has been happened with the Sea-Watch 3 last week, the Alex ignored Salvini’s ban and forced its way to the port, angering the interior minister. “Jackals!” tweeted Salvini. “They should go to prison!”

The German and French governments have stepped up their criticism of Italy over its handling of the recent cases of refugee landings. France accused Italy on Tuesday of acting hysterically over immigration and failing to live up to its duties.

The German interior minister, Horst Seehofer, wrote to Salvini asking him to rethink his policy, sources close to the German government said.

“We cannot be responsible for boats with people rescued from shipwrecks on board spending weeks on the Mediterranean because they can’t find a port,” Seehofer wrote.