OTTAWA (AFP) - Canada will tighten its rules on entering the country next month, adding a layer of security that will have an impact on Europeans and others previously allowed to visit without a travel visa.

Formerly visa-exempt foreign nationals, including those passing through on a stopover, will have to fill out an online Electronic Travel Authorisation (eTA) in advance and pay a small administrative fee of C$7 (S$7), starting from March 15.

The measure is similar to one set up by the United States in 2008, and will affect people from more than 50 countries.

Americans will be exempt. Anyone caught unaware of the new regulations can expect some leniency in the beginning, said Mr Robert Orr, Deputy Minister for Immigration.

He said the new rules will affect more than three million travellers per year.

After completing the online form, permission to travel to Canada will be sent by e-mail and will remain in effect for five years.

The eTA is meant to help the authorities better screen travellers for admissibility, Mr Orr told AFP.

He noted that Canadian security and intelligence agencies already do so but "not in a systematic way".

The United States, followed by Britain, France and China (whose citizens require a visa) are the top sources of tourists to Canada, according to government figures.