A UN team will be dispatched to Italy "to assess the reported sharp increase in acts of violence and racism against migrants, persons of African descent and Roma", said the body's new high commissioner for human rights, Michelle Bachelet, in her debut speech.
Observers will also be sent to Austria, she said.
While Bachelet was critical of the European Union's policies on migrants as a whole, she singled Italy out for what she called "political posturing".
"The government of Italy has been denying entry to NGO rescue ships," she said.
"This kind of political posturing and other recent developments have devastating consequences for many already vulnerable people. Although the number of migrants crossing the Mediterranean has fallen, the fatality rate for those making this treacherous crossing has in the first six months of this year been even higher than previously."
Interior Minister Matteo Salvini, the architect of Italy's new "closed port" policy, slammed Bachelet's comments as "biased" and "misinformed".
"Italy has over the last few years accepted 700,000 immigrants, including many illegals, and never got any help from other European countries," he railed on Twitter.
"So we won't take lessons from anyone, least of all the UN."
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Salvini also insisted that there was no reason to believe that racism was on the rise in Italy, despite a recent spike in reports of racially motivated attacks. Dozens of incidents have been reported since the new administration took office in June, ranging from verbal abuse and intimidation to serious, even fatal, violence.
A recent survey by the Pew Research Center, conducted after Italy's election but before the new government was formed, scored Italians highest out of 15 European countries on a scale of nationalist, anti-immigrant and anti-religious minority attitudes.
Opponents of the government, a coalition between Salvini's anti-immigration League and the populist Five Star Movement, accuse Italy's new leaders of stoking a "climate of hatred", a charge that Salvini has dismissed as "nonsense".
As well as barring entry to migrants rescued as sea, the interior minister has promised to deport undocumented immigrants en masse and compile a "register" of Roma people in Italy. He has accused immigrants – including those in Italy legally – of committing a disproportionate number of crimes and allied himself with Hungary's far-right prime minister Viktor Orban in a call to "defend" Europe's borders from migrants.
Bachelet, who before joining the UN was twice president of Chile, used her first speech to denounce such rhetoric.
"Historically, people have always moved in search of hope and opportunities," she said. "Erecting walls; deliberately projecting fear and anger on migrant communities... such policies offer no long-term solutions to anyone – only more hostility, misery, suffering and chaos.
"It is in the interest of every state to adopt migration policies that are grounded in reality, not in panic; which provide opportunities for safe, regular movement instead of forcing people to take lethal risks."
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Photo: Filippo Monteforte/AFP