"The ball is in Switzerland's court" – this message by the spokeswoman of the European Commission to journalists at the daily press briefing on Monday (10.02.2014) summed up the tight-lipped reaction by many in Brussels to Sunday's vote in Switzerland "against mass immigration."

The result of the referendum – a very slim majority in favor of limiting migration to Switzerland, which would largely affect EU citizens – was met by European officials with a mixture of surprise and disappointment. The European Commission said it "regretted" the result of the referendum and that the EU would now "examine the implications of this initiative on EU-Swiss relations as a whole."

"This goes against the principle of free movement of persons between the EU and Switzerland," an official Commission statement read.

'Bad news for Europe'

Some warned that Switzerland may lose its privileged access to the European single market. "There will be consequences. That's clear," said Luxembourg foreign minister Jean Asselborn,who had come to Brussels for a regular meeting with his EU colleagues. "You can't have privileged access to the European internal market and on the other hand dilute free circulation."

German foreign minister Frank-Walter Steinmeier said that "Switzerland has rather damaged itself with this result," adding that "Switzerland must realize that cherry picking with the EU is not a long-term strategy." German finance minister Wolfgang Schäuble also warned that the result "is going to create plenty of problems for Switzerland in a host of areas".

And French foreign minister Laurent Fabius spoke of a worrying result because Switzerland was isolating itself. He called the result "paradoxical," because Switzerland does the bulk of its foreign trade – 60 percent – with European Union countries. It was "bad news for Europe," according to Fabius.

The European Parliament's President Martin Schulz insisted it was important to keep a cool head and respect the Swiss' democratic decision. But he added that "the Swiss government now has to work out which conclusions it draws from it and whether it is compatible with its agreements with the EU."

'Guillotine' clause killed off?

The Swiss government, which had not supported the initiative, now has three years to turn the result of the vote into legislation. The Alpine country is not a member of the 28-nation EU, but pacts with Brussels have ensured the free movement of citizens to and from the bloc since 2002 – and have given Switzerland access to the European single market in return.

Switzerland's Foreign Minister Didier Burkhalter played down talk of a major rift with Brussels on Monday, saying that "Switzerland is not going to rip up its deal with the EU on freedom of movement." But that could go against the so-called 'guillotine' clause in a package of seven accords between the EU and Switzerland. The clause says that if one deal is suspended, the others collapse, too. The other deals have to do with issues such as trade between the EU members and non-member Switzerland; agriculture, transport and research funding.

But the clause has never been applied. The European Commission has indicated that it intends to make use of it, should the Swiss government indeed adopt legislation limiting the freedom of movement of persons. But who decides on whether or not the clause is applied: all 28 EU member states? The majority of EU member states? The European Commission?

Legal experts will now have to get down to work, policy analyst Rainer Münz with Bruegel think tank believes. "Switzerland is now banking on countries like the UK," Münz told Deutsche Welle, "because David Cameron and other countries have been critical of the freedom of movement of EU citizens within the EU. Switzerland therefore hopes for some understanding from these countries, which are led by the UK."

Immigration will top European election agenda

The Swiss vote sends the wrong signal at the worst possible time for European leaders and the European Commission in Brussels, insiders are convinced, with European elections pending in May. Rebecca Harms, a member of the European Parliament with the Green party, cautioned that Brussels could not ignore how strongly the immigration issue plays with voters – also in EU member states. "The EU must also address the public unease about the future, which this referendum outcome is a symptom of," she wrote in a statement.

"There is a risk today that we could see some kind of a negative coalition of member states asking to limit the freedom of movement of EU citizens within the EU," senior policy analyst Yves Pascouau from think tank European Policy Center agreed.

The feeling is widespread," he told Deutsche Welle. "We'll have to wait and see how the member states react to the situation with regard to Switzerland. And we will have to wait and see how the discourse will develop over the European Parliament's campaign and elections."

Anti-establishment parties across Europe – from anti-euro party AfD in Germany to Marine Le Pen's far-right Front National in France – were quick to salute the Swiss. Britain's UKIP leader Nigel Farage said that "it is a great thing to be welcomed that the Swiss people now have the freedom to decide the number and skill level of who they wish to invite to work or stay in their country."

EU waiting for Bern

The precise details of the immigration quotas in Switzerland will now have to be worked out. "The question is not whether, but when this becomes law," Bruegel's policy analyst Rainer Münz told Deutsche Welle, because the Swiss electorate had voted in favor of a legal text, rather than an open question that would need parliament's approval.

European officials said they were now waiting for the Swiss government in Bern to inform them about concrete plans to turn the outcome of the vote into law. In the meantime, the existing bilateral accords between Switzerland and the EU remain in place.