The safe-haven franc has soared since the global financial crisis erupted, prompting many Swiss consumers to cross the border to shop in Germany, France or Italy, importing goods back to Switzerland and hurting the retail sector in the country.

The Swiss Competition Commission fined BMW 156 million Swiss francs ($163 million) on Thursday as a result of an investigation it launched in 2010 following complaints from consumers who had tried and failed to buy cars abroad from BMW and its Mini brand.

The regulator said a clause in BMW's contracts with dealers in the European Economic Area (EEA) banned sales to customers outside the zone in an attempt to block direct imports to Switzerland and protect its car dealers in the country.

"Customers in Switzerland could not profit from the significant exchange rate advantages," it said in a statement. "The sealing off of the Swiss market led to lower competitive pressure on the sales prices for new cars from BMW and Mini."

BMW said it plans to appeal against the fine within the legal deadline of one month.

"We categorically reject the accusations, the argumentation and the amount of the fine," said a spokeswoman for the German company, adding that BMW adhered to all laws governing both Switzerland and the EEA.

Taking the average exchange rate over the year from October 2010 when it launched the investigation, the Swiss regulator said BMW cars were 20-25 percent cheaper in Germany.

It said while direct imports of most car brands had soared since 2008, they had been relatively flat for BMWs and Minis.

($1=0.9545 Swiss francs)

(Reporting by Emma Thomasson and Christiaan Hetzner in Frankfurt; Editing by Erica Billingham)

• A Permanent Economic Emergency