The Maine National Guard is planning to deploy 100 soldiers and airmen along the Canadian border under an agreement signed by U.S. Attorney General John Ashcroft and Canadian Cabinet ministers.

The strategy of using 600 National Guardsmen to augment customs and immigration agents at the border was made formal on Monday.

Other security improvements include sharing of computerized fingerprints, an expansion of joint investigative teams comprising U.S. and Canadian forces, and an increase in the number of immigration officers deployed overseas.

Ashcroft rejected suggestions that National Guard troops meant a military reinforcement of what is known as the world’s longest undefended border. The 600 Guardsmen add up to about one for every 100 miles, Ashcroft noted.

But the Guardsmen should help overworked immigration and customs workers and speed up commerce at the border, he said.

Maine Gov. Angus King earlier suggested the use of Guardsmen to maintain the flow of a trade relationship worth more than $1 billion a day.

“In the month or so after the attacks, there were substantial backlogs at the border crossings and they became a real hindrance to commercial relationships in Canada,” King said. “We’re trying to make it easier for people to pass through yet still pass through adequate security.”

The Guard troops are expected to be called up in the next several weeks, but the exact number to be called up is unclear.

“For planning purposes only, the U.S. National Guard suggested approximately 100 people will be used for this mission [from Maine],” said Maj. Eldon Hardwick, deputy chief of staff for the Maine Army National Guard and Maine Air National Guard in Augusta.