An NGO rescue ship with five people onboard has been barred from landing in Italy, despite the new left-leaning government in Rome vowing to change the hardline immigration laws of the former interior minister Matteo Salvini.

The Alan Kurdi, operated by the German NGO Sea-Eye, has been awaiting a safe port since 31 August after rescuing 13 people fleeing Tunisia. Eight of them were allowed to disembark in Malta for medical reasons. The ship was named after the three-year-old Syrian boy who drowned in 2015. The ship asked if the five remaining passengers could land in Sicily.

But in an email sent in the evening by the Italian coastguard in Rome and seen by the Guardian, authorities refused to allow the landing, citing the security decree drafted by Salvini, who lost his job as interior minister when his coalition with the Five Star Movement collapsed earlier this month. M5S went on to form a new coalition with the leftwing Democratic party.

Salvini’s decree, which has been described by aid groups as a “declaration of war against the NGOs who are saving lives at sea”, aimed to put an end to the rescue missions of aid groups in the central Mediterranean and issued fines for vessels that brought asylum seekers to Italy without permission.

Sea-Eye tweeted: “We have sent a request to the Italian ministry of the interior, to see if the entry ban and the €1m [£890,000] fine would still apply under the new government. It does. The new government in Rome is apparently sticking to its tough stance on civil rescue teams.”

The new interior minister, Luciana Lamorgese, a career civil servant and specialist in migration policy, has promised to revise Salvini’s hardline immigration measures.

Prof Fulvio Vassallo, an expert on migration and asylum law from the University of Palermo, said: “Unfortunately, the effects of the security decree, introduced by the previous governing coalition between the M5S and Salvini’s League, will affect the first days of the new government.

“Salvini has built that decree as a diabolical machine, difficult to bypass at least until the ministers of the new government have full powers.”

Italy’s new government, led by Giuseppe Conte as prime minister, won a vote of confidence on Monday in the lower house of parliament. But before being able to exercise its full powers, it needs a final vote of confidence from the Senate, scheduled for about 6pm on Tuesday. At least until then, the hands of Conte and the new coalition seem to be tied, as at least two passengers aboard the Alan Kurdi have tried to jump into the sea because of the stress and despair onboard after a day of waiting.

One of Salvini’s last moves before leaving his office last week was to ban the entry of the Alan Kurdi, which had previously requested a port of safety from the Italian authorities.

Meanwhile, another charity vessel, the Norwegian-flagged Ocean Viking, operated by the French charities SOS Méditerranée and Doctors Without Borders, has saved a total of 84 people. At the moment, Ocean Viking has not yet asked for a safe haven to disembark passengers.