ROME (AP) -

The U.N. refugee agency urged Italy on Tuesday to grant asylum to migrants it recently sent back to Libya, saying Rome was violating the fundamental principle offering protection to people fleeing persecution.

In a formal letter of protest to the Italian government, the U.N. High Commissioner for Refugees said it had interviewed some of those Italy returned to Libya and found "a number" who might qualify for asylum.

In a bid to crack down on illegal immigration, Italy last week began sending migrants intercepted in international waters back to Libya without screening them for asylum first. The move set off protests from the United Nations and the Vatican as well as human rights and humanitarian organizations, which said Italy was breaching international law calling for the protection of refugees.

Each year, tens of thousands of migrants set off from Libya in boats organized by smugglers, paying thousands of dollars to reach Italy. Their destination is often the tiny Sicilian island of Lampedusa, which is closer to Africa than the Italian mainland.

To date, Italy has sent more than 500 people back to Libya.

UNHCR said it was concerned about the new policy, which "threatens access to asylum in the EU and which risks violating the fundamental principle" of accepting asylum seekers.

The United Nations and human rights groups are particularly concerned since Libya hasn’t signed the 1951 convention on asylum status and has neither asylum laws nor a system to accept and protect the refugees.

"We are asking the Italian government to readmit those persons who were sent back by Italy and are identified by UNHCR as seeking international protection," the agency said. "Their refugee claims could then be determined in accordance with Italian law."

Premier Silvio Berlusconi defended the new policy Tuesday, saying Italy will always hear asylum claims from those fleeing persecution. But he said the people who board the smuggling boats are just paying for a trip to Italy.

"They aren’t people who have been pushed by a special situation inside their countries where they are victims of injustice; they are recruited ... in a scientific way by organized criminals," Berlusconi said.

Interior Minister Roberto Maroni said the UNHCR should screen the migrants for asylum in Libya, and then send them to other European countries, not just Italy, if they qualify.

The dispute over Italy’s new policy came as the government planned to put its immigration crackdown to parliamentary confidence votes Wednesday and Thursday to ensure quick passage of proposed legislation that would make it a crime to enter or stay in Italy illegally.

While Italy has long issued expulsion orders for people who arrive in the country illegally, the proposed legislation would make illegal presence in the country a crime, punishable by a fine of euro5,000-euro10,000 ($6,840-$13,670), although no prison penalty would be imposed.

In addition, the legislation imposes a prison term of up to three years for anyone who rents a room or apartment to an illegal immigrant.

A much-criticized provision that would have compelled Italians to report suspected illegal immigrants to police, setting up the scenario of "informers" or spies among doctors and teachers, was removed in recent days.

Surveys show many Italians link immigrants to crime, and the bill would authorize citizen anti-crime patrols in towns.

The minister for parliamentary relations, Elio Vito, told lawmakers Tuesday that the government will put the proposed legislation, in three parts, to separate confidence votes Wednesday and Thursday in the lower Chamber of Deputies.

Confidence votes force lawmakers to close ranks because any defeat would force the government’s resignation. Berlusconi’s forces have a comfortable majority in Parliament.

Italy is continuing to take migrants rescued in its territorial waters to holding centers on Lampedusa or Sicily.