A full 78.4 per cent of voters embraced changes made to the asylum law last September as applications soared to their hightest level in over a decade.
Opponents of the asylum law revision, which includes the removal of military desertion from a list of valid grounds for seeking asylum in Switzerland, voiced deep disappointment at their defeat.
"The referendum is a disaster for asylum seekers and refugees and leaves no winners," the committee that had requested the vote on the changes said in a statement, hailing the "minority of the population that still has a conscience".
"We knew in advance that we would lose," she told AFP, pointing out that the Swiss have repeatedly voted to tighten their asylum law since it went into effect in 1981, "but that it was this bad was very disappointing."
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Celine Amandruz of the populist Swiss People's Party (SVP), however welcomed the strong support for the tougher law, insisting that nine out of 10 people who seek refuge in the wealthy country did so "for economic reasons".
One of the most controversial revisions was the removal of military desertion as a valid reason for asylum.
That has been the key reason cited by Eritreans, who accounted for most applications to Switzerland last year and whose country imposes unlimited and under-paid military service on all able-bodied men and women.
The revision also removed the possibility, which had been unique in Europe, to apply for asylum from Swiss embassies -- a change opponents described as "inhumane", since it meant people unable to make the often dangerous journey from their country to Switzerland would remain without help.
"Leaving people and their families for so long wallowing in uncertainty is unacceptable," she said recently.
The rejigged asylum law also clears the way for the creation of special centres for asylum seekers considered to be trouble-makers and limits the right to family reunification to spouses and children.
Many opponents complained today that Sommaruga had mixed harsh tightening measures in with the legitimate change of shortening the application handling process -- which can drag on for years.
Switzerland currently counts some 48,000 people in the process of seeking asylum, including 28,631 who arrived in 2012.