The far-right Swiss People's Party, the country's largest, on Tuesday filed a petition supporting a cap on immigration to Switzerland, where more than a fifth of the population is foreign.

Party leader Toni Brunner said he wanted to "spark a debate on immigration" as he filed the petition to the federal chancellery, ending a months-long campaign to gather the required 100,000 signatures.

If the authorities deem the terms of the popular initiative legitimate, it then goes to a popular referendum, as per Switzerland's unique system of direct democracy.

The move is aimed at capping the annual number of foreigners granted residency and cherry-picking applicants. The party's proposals also include giving priority to natives on the job market.

Brunner's populist party also explained during the seven-month campaign that immigration quotas would be set in order to suit Switzerland's economic needs.

The country's federation of employers and industries promptly reacted to the prospect of a referendum by warning that the proposed law would threaten Switzerland's economic prosperity.

According to the party's own figures, the petition mustered a total of 136,195 signatures, the vast majority of which came from the German-speaking regions where Switzerland's far-right has its strongholds.

In August last year, foreigners accounted for 22.3 percent of the country's 7.9 million population.