About 100 Mexicans with travel plans to Canada camped outside the Canadian Embassy in Mexico City overnight to get a first crack at submitting their visa applications, and local media reports said the numbers swelled to 1,000 by mid-morning Wednesday.

The Canadian government announced suddenly Monday that it was imposing visa restrictions for the first time on Mexican nationals, giving people 48 hours to get their papers in place.

The move was a response to a rapidly growing number of refugee claims made by Mexicans who show up on Canadian soil.

Worried Mexican travellers and politicians criticized the Canadian decision Wednesday.

Opposition senator Graco Ramirez, of the Party of the Democratic Revolution (PRD), told Mexico's W Radio that the government should respond by imposing visas on Canadian travellers.

"The principle of reciprocity should be used with great precision … without causing a diplomatic war," Ramirez said. "But at least Mexican authorities should have the decorum to respond firmly. If this treatment is going to happen, it should be reciprocal."

The government's leader in the senate, Gustavo Madero Munoz, told the EFE news agency the visa requirement was a "terrible step backward."

He acknowledged the change was linked to the massive number of refugee claims launched by Mexicans — 9,400 last year — and said he would do everything possible to restore Canadian confidence in his people.

Complaints over embassy service

Would-be tourists complained of a lack of organization at the embassy.

"People who are giving information don't speak Spanish, and they treat us with disrespect," said Orlando Medina, who told La Reforma newspaper he had a ticket for July 20.

Some told local reporters they had decided to cancel their trips.

"They can't guarantee that they'll give us a visa, so we're not going to Canada," Lety Zetune told Televisa.

A dog exhibition judge named Cesar rushed to the embassy before catching a flight to Brazil. He was scheduled to travel to Canada on July 22.

"At the moment, I'm cancelling my invitation by the Canadian Kennel Club to judge," he said.