Official preliminary results showed that 63.7% of voters gave their backing to new EU gun laws, including tighter controls for semi-automatic weapons. A majority of voters in all but one canton, the Italian-speaking Ticino in southern Switzerland, came out in favor of reforming Swiss gun laws.

Read more: Switzerland votes on changing gun laws to fit with EU rules

Although Switzerland is not an EU member state, voters were told it must adopt the bloc's laws or risk being excluded from Europe's open-border Schengen system and the Dublin Accord for handling asylum applications.

Swiss lawmakers had approved earlier reforms that the EU deemed sufficient to comply with its legislation, however, that prompted a huge pushback by the rightwing Swiss People's Party (SVP), which gathered enough signatures to force Sunday's vote on the measures.

Banned firearms

Switzerland has one of the highest rates of gun ownership in Western Europe, according to the Geneva's Graduate Institute of International and Development Studies: More than 27% of the Swiss population own firearms.

Under the new gun law, semi-automatic weapons with high-capacity magazines would be listed as "banned."

Collectors and sports shooters could still purchase such firearms, but would need to jump over more barriers to obtain an "exceptional authorization." Traditional Swiss gun clubs and the SVP oppose the plans to restrict the ownership.

kw, es/sms (AFP, Reuters)

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