The German captain of a migrant-rescue ship who defied an Italian government ban to dock at the island port of Lampedusa expressed regret on Sunday for any alarm caused when her ship trapped a police boat against the quay.
Italian Interior Minister Matteo Salvini, leader of the anti-immigrant League party, called the incident "a criminal act, an act of war".
Carola Rackete, who was arrested on Saturday after spending two weeks in international waters with dozens of rescued African migrants, immediately switched off her engines when she realised the Sea-Watch 3 might have got too close to the patrol boat, her lawyer Alessandro Gamberini told Reuters by telephone.
"She is very sorry to have a created a situation of danger and fright among tax police officials. It was a difficult manoeuvre but she always felt she was conducting it in a safe way ... she had been approaching extremely slowly."
Government vessels had tried to prevent the Sea-Watch 3 docking and one ended up squeezed between the ship and the quay before freeing itself, videos on social media showed.
Rackete, 31, was arrested for resisting a military ship after being denied permission to dock under Italian laws introduced by Salvini to deter non-government rescue ships. She had been placed under investigation by Italian prosecutors last week on suspicion of aiding people-smugglers.
The interior ministry said the 41 migrants who disembarked the Sea-Watch 3, run by the German charity Sea-Watch, were "fed and spent a quiet night ... so it's unclear why the NGO needed to dock without authorisation".
But Sea-Watch's Italian spokeswoman Giorgia Linardi said Rackete had felt she could not keep the migrants on the ship for another night as suicide threats were forcing its crew to keep a constant watch.
Salvini says the European Union has left Italy alone to face the problem of arrivals by sea, and the issue has also caused considerable friction with Paris.
After French Interior Minister Christophe Castaner criticised Italy's approach, Salvini told Sky TG24 television that France should open its ports to two NGO boats that were in the Mediterranean.
"Every country, I reckon, is free to decide who comes in and who doesn't. Thousands of migrants are pushed back at the Italian border with France," Salvini said.
Salvini said the Lampedusa arrivals would be divided up between France, Germany, Luxembourg, Finland and Portugal.
"The head of the police will decide the size of the fine of between 10,000 and 50,000 euros against the NGO, and a magistrate has 48 hours to decide if the lady in charge of the ship that tried to squash four policemen like sardines deserves to remain in jail or not," Salvini added.
"If she is released, we have an expulsion order ready."