Voters in Switzerland are going to the polls to decide whether the country's strict rules on citizenship should be relaxed.

Being born in Switzerland does not guarantee citizenship. Non-Swiss residents must typically wait 12 years before applying.

Tests and government interviews are also required, which can be expensive.

The new proposal will allow third-generation immigrants to avoid some of that bureaucracy.

It will directly affect those born in Switzerland, whose parents and grandparents also lived in the country permanently.

Supporters of the plan to simplify the process argue that it is ridiculous to ask people who were born and have lived all their lives in Switzerland to prove that they are integrated.

However opponents suggest that the measures could lead to further steps that will eventually allow all non-Swiss residents - 25% of the population - to gain easy citizenship.

An opposition poster featuring a woman in a niqab suggests that the new proposal could lead to a so-called "Islamisation" of the country.

More than half the third-generation residents in Switzerland are descended from Italian immigrants. Other large groups have roots in the Balkans and Turkey.

Voting ends at 12:00 local time (11:00 GMT). First results are expected on Sunday afternoon.

The current vetting procedure, aimed at ensuring that new citizens are well integrated, includes interviews carried out by town councils. Questions put to interviewees can include requests to name local cheeses or mountains.

Those in favour of maintaining the current system also argue that the strict vetting rules make it superior to the more anonymous systems in neighbouring France and Germany.

Over the past 30 years, three previous attempts to relax the rules have been defeated. This time, opinion polls suggest the vote on Sunday will be close. Big cities back the idea, while more conservative rural areas oppose it.