ROME (AP) — U.N. human rights investigators have told Italy that a proposed decree formalizing the closure of Italian ports to aid groups that rescue migrants at sea violates international law.

In a letter to Italy's government, the investigators said the decree appears to be "yet another political attempt to criminalize search and rescue operations" that "further intensifies the climate of hostility and xenophobia against migrants."

Interior Minister Matteo Salvini, a hard-line populist, has proposed the decree ahead of the European Parliament elections this week, where nationalist, anti-migrant parties are hoping to make strong gains.

The letter from the U.N. High Commissioner for Human Rights says the measures would violate migrants' human rights, which are enshrined in U.N. conventions. It said Italy is obliged to rescue migrants in distress and cannot impede others from doing so.