Swiss voters go to the polls on Sunday to decide whether to tighten up their gun laws to conform with European Union regulations.

Switzerland is not a member of the EU, but is part of the Schengen open-border treaty.

After the 2015 Paris attacks in which 130 people died, the EU issued Schengen members with new restrictions on automatic and semi-automatic weapons.

The EU hopes the rules will help police in Schengen countries.