The Swiss have held a referendum on a government move to tighten the country's asylum law amid a spike in refugees, with early results and opinion polls suggesting a vote in favour.

Shortly after polling stations closed on Sunday at noon (1000 GMT), nine of Switzerland's 23 cantons had accepted changes made to the asylum law last September, according to results given by public broadcaster RTS. The most recent poll in late May showed 57 percent of Swiss in favour of the tougher asylum rules.

The amendments included removing military desertion from a list of valid grounds for seeking asylum in Switzerland Military desertion had been the grounds for asylum most frequently cited by Eritreans, who accounted for most applications to Switzerland last year. Eritrea imposes unlimited military service, with low wages, on all able-bodied men and women.

The revision, which took effect last September, also removed the possibility - which had been unique in Europe - to apply for asylum from Swiss embassies instead of travelling to Switzerland to do so. Opponents have described the change as "inhumane".

Justice Minister Simonetta Sommaruga insisted the changes were needed and stressed that they have significantly speeded up the application process.

"Leaving people and their families for so long wallowing in uncertainty is unacceptable," she said recently.

Switzerland currently counts 48,000 people in the process of seeking asylum, including 28,631 who arrived in 2012.

The surge, attributed in part to the Arab Spring uprisings, marks the highest number since the Balkans war in 1999, when nearly 48,000 people sought refuge in the country.