Trade and travel problems along the U.S-Canadian border remain a serious aggravation for the government of Prime Minister Stephen Harper, Canada's ambassador to Washington said on Monday.

We call it a thickening of the border, said Canadian Ambassador Michael Wilson, referring to a slew of issues that Ottawa fears will hold up commerce with the United States, Canada's most important trade partner.

Keeping trucks and tourists rolling into the United States is vitally important with two-way trade of about $1.5 billion every day, Wilson said in an interview with Reuters.

Canada has been frustrated by Washington's decision to impose new fees for Canadian travelers and truckers crossing the 3,985-mile (6,413-km) border with the United States.

U.S. officials say the move, which ended Canada's 15-year exemption from such fees, was needed to ensure the safety of food and other imports. But it brought complaints about costs and worries over shipping delays from businesses on both sides of the border.

The new rules from the U.S. Department of Agriculture's Animal and Plant Health Inspection Service and U.S. Customs and Border Protection include fruit and vegetable inspections and a $5 fee for each airline passenger arriving from Canada.

This to us is little more than a tax ... it just slows things down at the border, Wilson said.

Also problematic, he said, is confusion about U.S. document requirements for Canadian travelers, which has led to a delay of up to 14 weeks for Canadians seeking new passports.

The Bush administration has moved to tighten document rules for travelers coming in and out of the United States, but it has postponed requirements for some countries like Canada as swamped U.S. passport offices struggle to deliver documents for thousands of would-be travelers.

The security aspects of this we don't have an argument with ... where we do have a concern is on the implementation, Wilson said.

Canada would like to see the United States consider measures like phased implementation of changes that might avoid interrupting travel and trade does have a very real economic impact, he said.

BEEF ON BEEF

Ottawa is also growing impatient about another border issue as it awaits word on a rule that would allow Canada to export older cattle, and meat from older cows, to the United States.

Washington had limited cattle and beef imports from Canada because of fears about mad cow disease. Canada has reported 10 cases of the disease, bovine spongiform encephalopathy, since 2003.

Wilson said Canada's case was strengthened by a decision last month from the World Organization for Animal Health that put the United States and Canada in the same risk category for mad cow disease.

We would have liked to have had a resolution for this sooner than now, he said.

A U.S. decision to accept all Canadian beef imports and cattle born on or after March 1, 1999 could prompt other countries to follow suit, he said. If Washington stalls, other nations might do the same.

U.S. Canada