OTTAWA - Canada's crackdown on human smugglers is legitimate and defensible under the charter, Immigration Minister Jason Kenney said.

Kenney appeared before a Senate committee Monday to defend Bill C-31, the government's major reforms to the immigration and refugee system.

Included in the proposed legislation are a host of measures meant to send a message to human smugglers that Canada will no longer be an easy mark for their syndicates.

The bill would implement mandatory minimum sentences and higher penalties for human smugglers. It would also have mandatory detentions for people coming into Canada through smuggling operations for two weeks without review and would ban them from applying for permanent residency for five years.

Critics have raised concerns about those provisions, warning that some smuggling reforms may not comply with requirements under the Charter of Rights and Freedoms.

Not so, said Kenney.

"The government's view is that all the provisions in the bill are defensible under the charter," he said.

He said the government's aim was to make Canada less attractive for both human smugglers and their victims, while ensuring legitimate refugees - even those smuggled into Canada - get a fair and timely hearing.

Furio De Angelis, the Canadian representative for the UN Refugee Agency, praised the government for introducing an important amendment in May that reduced the detention period with no review from a year to two weeks - originally one of the most heavily criticized aspects of C-31.

But he told senators Monday he was concerned the bill would still create two separate classes of refugees and punish those who felt they had no choice but to resort to using smugglers to reach safety.

"Why human smuggling remains a scourge at the global level is that sometimes asylum-seekers have no alternative," De Angelis said, adding that the UN nonetheless supported "in principle" efforts by countries to fight human smuggling.

Bill C-31 is currently at second reading in the Senate and is expected to pass into law before the end of June.