Italy’s government is planning to issue a decree that would mean NGO rescue boats would be fined up to €5,500 (£4,760) for each migrant they disembark on to Italian soil.

Aid groups said the planned decree from Matteo Salvini amounted to a “declaration of war against the NGOs who are saving lives at sea”.

The far-right interior minister’s decree – which will be proposed to the council of ministers in the next few days and then voted upon by parliament – would allow NGOs to be fined “from €3,500 to €5,500 for each transported foreigner”, according to draft text seen by the Guardian.

In the most serious cases, the licenses or authorisation to transfer people on board will be suspended for one month to a year.

The new decree reinforces the powers of the ministry of the interior in the matter of immigration and has the objective of putting an end to the NGO rescues. Médecins Sans Frontières, for example, would have had to pay €440m for saving 80,000 people if the decree had been in place during the last three years.

“The new decree is threatening legal principles and the duty of saving lives,” said Claudia Lodesani, president of MSF Italy. “It is like fining ambulances for carrying patients to the hospital.

“The draft text of the security decree misinterprets the navigation code and the very basis of the international law applicable to the search and rescue,” Giorgia Linardi of Sea-Watch said. “The lives of people are reduced to a fine: a fine that actually goes to punish what is a moral and legal duty and a human act of solidarity.

“It shows the weakness of a government that is not able to guarantee control through democratic means and rather constantly feels the need to resort to the threat of using law enforcement.”

“The new rules contradict the constitution,” Italian senator Gregorio de Falco, who is also a former coastguard official, told the Huffington Post. “It means that those who save lives have to pay. But it must be borne in mind that those who do not save people go to jail because we have an obligation to save people in distress.”

Last year, De Falco was expelled by the M5S Movement, which governs in coalition with Salvini’s party, the League, for voting against a previous security bill, the so-called “Salvini decree”, drafted by the interior minister and targeting asylum rights.

The decree left hundreds in legal limbo when its removal of humanitarian protection for those not eligible for refugee status but otherwise unable to return home was applied by several Italian cities soon after its approval by parliament in December 2018.

Salvini has repeatedly declared Italian waters closed to NGO rescue vessels. Several boats have been left stranded at sea because of this hardline approach, which is partly designed to force other parts of Europe to take in more people.

“Instead of criminalising NGOs that rescue migrants, Italy should mourn the victims of the latest tragedy at sea,” says Lodesani.

Last Friday, up to 70 people trying to reach Europe from Libya drowned after their vessel capsized in the deadliest such incident in the Mediterranean since January.

According to survivors, at least 16 of whom were rescued, the boat left Zuwara in Libya, where renewed warfare between rival factions has gripped the capital, Tripoli, in the past five weeks. The vessel capsized 40 miles (64km) off the coast of Sfax, south of Tunis, as it headed towards Italy.

So far this year, 17,000 people have sought refuge in Europe via the sea, about 30% less than in the same period last year, according to the International Organization for Migration. The IOM said 443 people had reportedly died on Mediterranean crossings since 1 January, compared with 620 in the same period in 2018.

The Institute for International Political Studies (ISPI) thinktank said that one person died for every eight people who left Libya between January and April, based on analysis of figures from the Italian interior ministry.

The NGO ship Sea-Watch 3 is currently sailing across the Mediterranean towards Libya.

“They better not think of putting migrants on board,” said Salvini. “We’ll stop them by any means necessary.”