Some law enforcement officers in the United States say certain points along the border with Canada pose a serious security risk because they are easy to cross unnoticed.

Officials are especially concerned about 37 isolated border crossings operating on an honour system.

One of them is at Angle Inlet, where Manitoba meets Minnesota on a peninsula in Lake of the Woods. The border crossing has an unstaffed wooden shack where people talk to an American customs agent 80 kilometres away using a videophone.

The technology often does not work and officials estimate one in three people don't bother checking in.

Dallas Block, sheriff of Minnesota's Lake of the Woods County, told CBC News he has seen an increase in drug trafficking in the area and has intelligence that suspected terrorists have come to check the area out.

"I think it should be a huge concern. We live in a whole new world with terrorism. There's a big emphasis on the southern border and I think we need to be concerned about the northern border," he said.

"I want people on the northern border to be vigilant. I would hate to have it said that if something happened – if somebody came through here with something – [that] we weren't being vigilant."

Block would like to see federal governments on both sides of the border invest more resources to staff crossings.

Cost too high?

But Colin Kenny, head of the Canadian Senate's standing committee on national security and defence, said the idea is not feasible.

"If you have more funds available, you can have better intelligence and perhaps catch people that way. But I don't think you can afford to have full-time coverage at places that aren't used by people," he said.

"The crossing that we're talking about, in particular, it's my understanding that it leads to a body of water and it's not really a very convenient way to get across the border."

Angle Inlet is surrounded by water on three sides; a person attempting to sneak into the United States at that point would have to travel by boat or snowmobile to reach the mainland.

Kenny says it is important for people living along the border to watch for suspicious activity and report it to the local authorities.