Washington ? U.S. officials, already concerned about illegal drugs coming across the Canadian border, are warning that a Canadian plan to decriminalize marijuana use could lead to more inspections and long border delays.

“We don’t want the northern border to be a trafficking route for drugs,” said Asa Hutchinson, undersecretary for border and transportation security for the Department of Homeland Security.

Hutchinson and other U.S. officials say the Canadian proposal is especially troublesome, considering how drug seizures along the vast northern border soared after the Sept. 11, 2001, terrorist attacks — in part because of heightened security. The amount of marijuana seized from Canada quadrupled in the year after the attacks.

Seizures have subsided slightly since, but remain well above historic levels.

If Canada approves a plan to decriminalize marijuana for personal use, U.S. officials fear drug smuggling could spike, further burdening the justice system and hindering trade. More vehicles may be stopped and searched at checkpoints along the 4,000-mile border, slowing movement of the $1 billion worth of goods traded between the two countries each day.

“If the perception is that it’s easier to get marijuana in, then some border officials’ antennas will be up,” said Paul Cellucci, U.S. ambassador to Canada.

Canadian Prime Minister Jean Chretien’s administration introduced legislation in late May that would essentially make the penalty for possession of small amounts of marijuana equivalent to a traffic ticket. The bill would boost penalties for growing and trafficking marijuana.