Prime Minister Stephen Harper distanced himself from Mexico's president-elect Thursday as Felipe Calderon compared a U.S. plan to build more fences along the southern border to the Berlin Wall.

Hours after U.S. President George W. Bush signed a bill authorizing more than 1,100 kilometres of new fencing along the U.S.-Mexico border, Harper said there are different challenges along the 49th parallel.

"Obviously, the situation along the Mexican-American border is different than the Canadian-American border," Harper said at a joint news conference with Calderon in Ottawa.

Calderon called the fence plan "deplorable," predicting it would lead to the deaths of more Mexicans at the southern border. More than 400 Mexicans have already died during 2006 in attempts to cross it.

"Humanity made a huge mistake by building the Berlin Wall and I believe that today the United States is committing a grave error in building the wall on our border," Calderon said. "It is much more useful to solve common problems and foster prosperity in both countries."

Harper has said he "spoke aggressively" with Bush against U.S. proposals for tightened restrictions for travellers along the U.S.-Canada border.

PM decries 'unnecessary barriers'

Calling Calderon "a man of strong principle" with a "realistic political and economic vision," the prime minister said "unnecessary barriers between our countries" limit trade, economic growth and tourism.  

Harper said the two talked about ways to strengthen the North American Free Trade Agreement while respecting the issue of border security and the need for "a safer and more economically viable" continent.

In Washington, Bush called the bill authorizing fences along the U.S.-Mexican boundary "an important step in our nation's efforts to secure our borders."

Mexico has objected to the fences as an ineffective measure as long as the two countries haven't resolved the core issues that surround illegal migration.

The government points out that most illegal workers don't cross the border by foot, and that the millions spent on the fences could have been put towards improving roads.

Calderon calls guest worker program 'success story'

Calderon said Canada's guest worker program was a "success story" for both countries because it gave Mexicans an opportunity to earn a legal, decent income while Canadians benefited from the hard work of Mexicans in areas where it is critically short of labourers.

Calderon, while acknowledging Harper was not Canada's official head of state, also invited the prime minister to his inaugural ceremonies on Dec. 1.