Despite an unemployment rate that spiked in 2009 and remains high, the number of temporary foreign workers in Canada has more than doubled over the last six years, according to the Conference Board of Canada.

In 2006, there were 150,000 temporary foreign workers employed in Canada. By December 2012, that number had more than doubled to 340,000.

The growth in the number of foreign workers continued throughout the 2009 recession, when the unemployment rate peaked at 8.6 per cent. In June of this year, unemployment stood at 7.1 per cent, though joblessness among young workers was stuck around 14.1 per cent.

The temporary foreign worker program has come under scrutiny in the last four months, since CBC reported that professional IT workers were being fired from their jobs at RBC so the employer could bring in temporary foreign workers.

The federal government amended the rules in late April, making it more difficult and more expensive for companies to turn to foreign workers to fill job vacancies in Canada. But the impact of those rule changes has yet to be seen, the Conference Board says.

Its report released Tuesday says that while Canadian youth were struggling to secure employment, especially that important first job after college or university, companies continued to bring in foreign workers in record numbers.

"This, justifiably, raises the question: if the unemployment rate remains relatively high and so many young and able Canadians are unable to find work, why are we still bringing in so many people under the TFW program?" the Conference Board asks.

There is no clear answer to that question, it concludes, pointing out that Alberta faced looming labour shortages in 2006. Employers in some parts of Alberta and Saskatchewan continue to have difficulty finding workers, despite the number of jobless in Canada.

A CBC report last month found the number of foreign workers in Canada had nearly tripled over the past 10 years.

The Conference Board blames a skills mismatch and the reluctance of Canadians to move long distances to find work for the inability of employers to attract Canadian workers to jobs. There also may be perception that foreign workers can be hired for less than their Canadian counterparts, the report said.

One of the key changes that Ottawa announced in April is a new fee that will be imposed on employers when they apply to the government for a labour market opinion (LMO). A positive labour market opinion must be obtained in order for employers to bring foreign workers to Canada. It takes a number of factors into consideration including what potential benefits hiring the foreign workers would have on the labour market and what efforts were made to hire Canadian workers for the positions.

The government also got rid of a rule that allowed employers to pay foreign workers up to 15 per cent less than the prevailing wage for a classification of job.

The Conference Board said it expects these changes to put "downward pressure" on the number of foreign workers in Canada — and lead to more employers seeking out domestic workers for jobs. However, it is too soon to tell if the measures will be effective in lowering the number of temporary workers in Canada while unemployment is high, the report said.