The 31-year-old German national faces up to 10 years imprisonment for the act which breached the Italian authorities’ ban.

In an open letter sent to Italian counterpart Enzo Moavero Milanesi, Asselborn wrote that the capital had been “obliged to bring 40 migrants to Lampedusa.”

“Saving human lives is a duty and should never be a crime […] On the contrary, not saving someone is a crime.”

According to Italian sources, a police speedboat tried to block the entrance to the port. The speedboat moved to avoid being struck by the larger Sea-Watch 3, a confrontation which Italy’s right-wing interior minister Matteo Salvini described as “an act of war”. Rackete was placed under house arrest, and the ship was confiscated, according to Spiegel online.

The letter, published on Facebook on 29 June, is reproduced in full below:

Regarding: Carola Rackete, captain of the NGO Sea-Watch.

Dear Enzo, minister of foreign affairs of Italy,

A lot of people, in your country as in mine, know, that we are both not only colleagues but also friends. This allows me to address you these few words in a non-conventional, fast and direct way on social networks.

I would like to request your help, by this way, so that Carola Rackete, who was at the helm of the vessel bearing a Dutch flag and who was obliged to disembark 40 migrants in Lampedusa, today on 29 June, be released.

Saving human lives is a duty and can never be an offence or a crime; not to save them, on the contrary, is one. As in the past, Luxembourg will remain sensitive to the idea of solidarity with Italy with regard to the distribution of migrants rescued by ships from NGOs in the Mediterranean.

With all my friendship, dear Enzo, I would like to thank you for your understanding.

Jean