A group of Swiss environmentalists has collected enough signatures to force a national referendum on immigration.
The Ecopop group says natural resources are under increasing pressure from overpopulation.
It wants annual population growth through immigration capped at 0.2% and a tenth of foreign aid to be used for birth control measures abroad.
Switzerland now has a population of eight million people – almost a quarter of them foreigners.
Ecopop gathered a petition with 120,700 certified signatures – easily passing the 100,000 threshold needed for a referendum on the proposed new law.
“The pressure on land, nature and the countryside is considerable, and quality of life is continuously deteriorating due to a lack of living space,” said Ecopop member Philippe Roch, a former director of the Swiss environment department.
The group insists it is opposed to all forms of xenophobia and racism but says Switzerland must limit immigration to avoid urbanisation and to preserve agricultural land.
Under the Swiss system of direct democracy, referenda take place up to four times a year.
Correspondents say the initiative reflects growing concern in Switzerland about overcrowding. The population has risen by some 15% since 1990.
In April, the Swiss government agreed to re-impose immigration quotas on workers from central and eastern EU countries – a decision criticised by EU officials.
Until 2011, Switzerland had a quota of 2,000 residency permits per year for citizens of the so-called “A8” nations, which joined the EU in 2004.
The right-wing Swiss People’s Party (SVP), which blames rising rents and crowded transport on immigration, has also gathered enough signatures to force a referendum on tougher immigration quotas.