Tough new measures to fight illegal immigration and crime became law in Italy on Thursday after the Senate gave the green light to a bill contested by the centre-left opposition and the Catholic Church.

The law makes illegal immigration a crime punishable with a fine of up to 10,000 euros ($14,000) and raises to six months the amount of time that illegal migrants can be detained in holding centres before repatriation.

It also allows the creation of unarmed citizen patrols to help police and soldiers fight crime on the streets, makes it a jail offence to force children to beg, a measure viewed as targeting gypsies and Roma people.

The law was put forward by Interior Minister Roberto Maroni, a member of the anti-immigrant Northern League which is a crucial ally for Prime Minister Silvio Berlusconi's conservative government, elected last year on a law-and-order ticket.

"We want to tell citizens that the government is acting to guarantee their security," he said on Thursday, after the government won three confidence votes on the bill.

In a heated debate at the Senate, centre-left lawmakers accused the government of violating the rights of immigrants and said the citizen patrols risked becoming vigilante groups taking the law into their hands.

The Catholic Church has also repeatedly criticised the measures, which civil rights groups say could deter illegal immigrants from seeking hospital treatment or enrolling their children in school for fear of being reported to police.