BRUSSELS — The choice by Swiss voters to impose new curbs on immigration is sending shockwaves through the European Union. The bloc's leaders warn it violates the "sacred principle" of freedom of movement and politicians worry about its impact on other anti-immigration pushes. Here's a look at the issue:

With more than one million EU citizens living in Switzerland, there could be far-reaching political and economic consequences to Sunday's 50.3 percent "yes" vote in favor of imposing quotas on foreign workers.

Although Switzerland isn't a member, it has close ties to the 28-nation bloc that were hammered out in a 1999 package of agreements on everything from government procurement to scientific research.

The vote puts that in jeopardy. The Alpine country was granted free and privileged access to the world's biggest market only because it agreed to free movement between borders, points out Luxembourg's Foreign Minister Jean Asselborn.

The Swiss government opposed a "yes" vote, but it must now submit a proposal to Parliament on how to implement the limits approved by voters. The justice minister says that will happen as soon as possible.

Limits and quotas will apply to foreigners, including cross-border commuters and asylum seekers. Businesses must give Swiss nationals priority when hiring. But the referendum did not specify how generous the quotas should be, who should set and allocate them or what the criteria for doing so should be.

Changes approved by voters also limit foreigners' ability to bring in family members or to access Swiss social services, and cut back on asylum seekers.

The EU says until Swiss law is rewritten or there is a change in government policy or actions, nothing has changed.

"It is up to Switzerland's government to decide if they want to suspend the agreements with us or not," European Parliament President Martin Schulz said during a visit to Israel. "So long as Switzerland will not react, the agreements exist."

Some European leaders are warning of serious consequences. The 1999 agreements include "a so-called guillotine clause that holds that if one of the elements is challenged — in this case, on the free circulation of workers — then everything falls apart," French Foreign Minister Laurent Fabius told France's RTL radio.

If EU leaders decide that Swiss authorities have breached the accords, the "guillotine" may then fall on seven separate bilateral agreements.

In addition to EU citizens living in Switzerland, another 230,000 cross the border daily for work. Some 430,000 Swiss reside in member states of the European Union. All these people could suddenly find themselves in legal limbo.

The first tripwire may come over whether citizens of Croatia, the newest member of the European Union, can freely enter Switzerland the way nationals from other EU member states do.

European Union officials were expecting the Swiss to grant Croatians that right effective July 1. If the Swiss now balk there would be "quasi-automatic" consequences for Switzerland's chances to participate in upcoming EU research and educational exchange programs, a top EU official said.

The official spoke on condition of anonymity because he was not permitted to speak publicly.

The EU is the most important economic and political relationship for Switzerland so any changes could be momentous.

"Switzerland lives economically off its exchange with its European neighborhood. Its exchange of goods with (the German state of) Baden-Wuerttemberg is bigger than that with the United States," German Foreign Minister Frank-Walter Steinmeier said. "I think Switzerland has harmed itself with that result."

Its banks, UBS and Credit Suisse, and companies like Zurich Insurance, are staples of the European financial scene. Europeans are enthusiastic consumers of Switzerland's chocolates and luxury watches.

If the EU decides to make it more difficult for Switzerland's businesses to operate, the cost to the country could be huge.

In 2012, according to European Commission, the EU's executive arm, the European Union's exports of goods and services to Switzerland totaled a little over 216 billion euros ($293 billion) and imports around 165 billion euros.

As the European economy stubbornly refuses to grow, ranks of anti-immigrant parties have swelled in Britain, Greece, France and elsewhere. Those parties may make an unprecedentedly strong showing in elections for the European Parliament this spring.

"We are seeing throughout Europe the rise of what can only be called the far-right agenda," Irish Foreign Minister Eamon Gilmore said.

The vote was hailed by Germany's far-right National Democratic Party, which said "Switzerland has shown it's possible to campaign against mass immigration. The German people would vote similarly, if they were asked."

Nigel Farage of Britain's UK Independence Party, who hopes to add to the party's 13 seats in the European Parliament, said the vote showed free movement within Europe "is unsustainable."

In France, the leading far-right group, the National Front, has made anti-immigration a perennial platform plank, and party leader Marine Le Pen credited Swiss voters with showing "lots of good sense."

Ironically, in Italy those most upset about the Swiss vote were the anti-immigrant Northern League. Their party power base is in Lombardy, where tens of thousands of Italians commute to work in Switzerland every day.