WASHINGTON – A controversial civilian patrol group that has been monitoring the Mexican border for illegal immigrants is looking to expand its mission to the Canadian border, organizers said this week.

Minuteman Project leaders said their volunteers this month alerted federal authorities to more than 330 cases of illegal immigrants crossing into the United States over a 23-mile stretch of Arizona’s southern border. Now they plan to extend their patrol along the rest of the border with Mexico and are helping to organize similar efforts in four states that neighbor Canada.

“In the absence of the federal government doing its mandated duty to secure our borders, we will pick up the slack. Reluctantly,” said Chris Simcox, a Minuteman co-organizer who also operates Civil Homeland Defense, another Arizona group that monitors illegal immigrants.

“We shouldn’t have to be doing this,” Simcox told reporters in Washington, where he was to meet with lawmakers Wednesday. “But at this point, we will continue to grow this operation – also to the northern border.”

Simcox offered no timeline on when the Canadian border patrol – to be organized in Idaho, Michigan, North Dakota and Vermont – might begin. But he said he hoped to start patrols near San Diego, Calif., by June and along the rest of the Mexico border by October.

Mario Villarreal, a spokesman for U.S. Customs and Border Protection, said his agency “does not endorse the expansion of civilian patrols, as proposed by the citizens group in Arizona. We must leave the responsibility of protecting the nation’s borders to the highly trained law enforcement personnel of the Border Patrol.”

“We’re not supportive of vigilantes,” said Dan Whiting, spokesman for Sen. Larry Craig, R-Idaho. “We can empathize with the need for border security, but we need to do it the right way.”

Several hundred Minuteman volunteers, some of whom were armed, were not allowed to detain illegal border crossers spotted during their April patrol. But immigration advocates and federal authorities raised concerns about the volunteers, and President Bush has said he is opposed to “vigilantes” and that the U.S. Border Patrol should enforce border security.

More than half of the 1.1 million illegal immigrants apprehended in the United States last year entered at the Mexico-Arizona border. Recent intelligence suggested al-Qaida terrorists might enter at that point.

The U.S. northern border along Canada is twice as long as the southern border along Mexico. Customs officials caught a man with explosives trying to enter Washington state from Canada in December 1999 in what has become known as the millennium terrorist plot.

The Minuteman organizers estimated it would take $4 billion and two years to completely secure the Mexico border, and $8 billion and three years on the Canada border.