Switzerland goes to the polls this weekend to decide on new regulations aimed at reducing the number of asylum seekers entering the country.
The electorate also has the final say on an amended law tightening immigration rules mainly for citizens from countries outside the European Union.
A third issue to be voted on is a proposal to prop up the country's ailing old age pension scheme with profits from the National Bank.
The government said harsher measures against asylum abuses were necessary to avoid social tensions and provide protection for those fleeing persecution.
The law, which was approved by parliament last year, was challenged to a nationwide vote by a coalition of centre-left parties, trade unions, churches and aid organisations.
During an emotional campaign in the run-up to Sunday's vote, opponents – notably the Social Democrats and the Greens – argued that the reforms went against Switzerland's humanitarian tradition and were in breach of international law.
They said the regulations would make Switzerland one of the most restrictive countries in Europe.
Under the new measures applicants who cannot produce identity papers within 48 hours without a credible reason are excluded from asylum altogether. All rejected asylum seekers are barred from regular welfare benefits and can apply only for food and shelter.
A controversial clause in the legislation will mean jail sentences of up to 24 months for those refusing to leave Switzerland.
Justice Minister Christoph Blocher of the rightwing Swiss People's Party – who is at the forefront of the reform – warned of an increasing number of asylum requests and high costs for the country's welfare system.
The amended law on foreigners in principle limits immigration for citizens outside the European Union and the European Free Trade Association (Efta) to highly skilled labour. It also aims to encourage integration, in particular by language courses, while cracking down on human trafficking and marriages of convenience.
The cabinet, as well as three of the four main parties, have come out in favour of the regulations, but opponents criticise the restrictions for family members of immigrants and harsh jail terms for illegal immigrants who refuse to leave the country.
There are also concerns that the legislation ignores the fate of the estimated 100,000 illegal immigrants who already live and work in Switzerland.
Latest opinion polls predict a clear victory for the supporters of the tougher asylum and immigration rules.
Old age benefits
The proposal to use some of the annual profits of the National Bank to plug expected shortfalls in the state pension scheme was launched by the Social Democrats and the trade unions.
It involves changing the current distribution plan which gives two-thirds to the country's 26 cantons, which enjoy a large degree of autonomy, while a third goes to the federal authorities.
The government, in addition to a majority in parliament, the business community, the cantons and the central bank, have come out against the plan which they say is not sustainable and fails to tackle the structural problems of the pension fund.
They also claim it would put the National Bank under undue political pressure and threatened monetary stability.
The vote is the latest in a series of proposals to ensure the financial future of the main tenet of Switzerland's social security system. It risks running up a huge deficit because of an increasing number of pensioners and longer life expectancy while the number of mandatory contributors has been on the decrease.
swissinfo, Urs Geiser
It is the ninth time since 1984 that Switzerland's asylum law has been amended. Five of the proposals to tighten the regulations were approved in nationwide votes.
Under a bilateral treaty agreed with Brussels, EU citizens are not subject to immigration restrictions. But there is a sizeable community of people from Balkan countries and Turkey living in Switzerland.
The old age pension scheme is the central pillar of the country's social security system which is funded by contributions from employers, employees and the state. It aims to provide minimum coverage for all people over 65 (men) and 64 (women).
The vote on old age benefits requires a majority of voters and cantons to pass at the ballot box.
The two referendums on tightening asylum and immigration rules need only a simple majority of voters.
About 4.84 million people over the age of 18 have the right to vote in Switzerland; the average voter turnout is around 40%.