The Swiss central bank pledged Thursday to defend the franc's exchange rate floor against the euro, while maintaining its record low interest rates.

The Swiss National Bank, which fixed a minimum exchange rate of 1.20 Swiss francs to the euro in September 2011, said it would "enforce this minimum rate with the utmost determination."

All traffic through an Alpine rail tunnel linking Switzerland and Italy was halted Wednesday due to a bomb threat, police and the national Swiss rail service said.

"The bomb threat was received at 11:15 am (1015 GMT) and all the traffic has been interrupted" through the Simplon tunnel linking the Swiss town of Brig with Domodossola in Italy, said Marcus Rieder, a police spokesman in the southern Swiss canton of Valais.

Germany said on Wednesday it had banned three Islamist Salafist groups which officials said aimed to sweep aside democracy and set up a system based on Sharia Islamic law.

The interior ministry said the bans, which come amid stepped-up observation of the Salafist community in Germany, took effect early Wednesday in the western states of Hesse and North Rhine-Westphalia.

Switzerland's government on Friday rejected calls to axe special rules allowing rich foreigners resident in the country to pay less tax, saying the current system still raised crucial revenue.

In a statement, the government said it had rejected demands by leftwing parties and trade unions on the grounds that existing system generates 668 million Swiss francs (539 million euros, $705 million) in taxes.

The Swiss National Bank on Thursday posted a 2012 profit of 6.9 billion Swiss francs (5.6 billion euros, $7.2 billion), nearly half of what it earned in 2011, owing to slipping income from foreign currency holdings.

In 2011, Switzerland's central bank, SNB, posted a profit of 13.5 billion Swiss francs.

Switzerland has the globe's most competitive travel and tourism sector owing to high quality transportion and hotels, skilled workers and rich natural resources, the Swiss-based World Economic Forum said Thursday.

In a biennial, 140-country ranking of competitiveness in the world's travel and tourism trade, the WEF said the Swiss had retained the top slot held in all five previous editions.

Switzerland confirmed on Thursday that one of its nationals taken hostage in Yemen a year ago has been freed and has arrived in the Qatari capital Doha.

Swiss news agency ATS said Foreign Minister Didier Burkhalter had already spoken to the woman by telephone.

Two people were killed and seven others wounded when a gunman opened fire in a Swiss factory on Wednesday, police said, adding the gunman also died.

"There are three dead and seven wounded, a number of them seriously," local police spokesman Simon Kopp was quoted as saying by news portal Blick.ch.

U.N. leader Ban Ki-moon condemned Tuesday North Korea's nuclear test as "deeply destabilizing" and U.S. President Barack Obama called for swift and credible international action.

Ban condemned the nuclear weapons test as a "deeply destabilizing" provocation, his spokesman said Tuesday.

Switzerland has refused to reopen long-running graft cases against Pakistani President Asif Ali Zardari as he enjoys immunity as head of state, Pakistan's law ministry said on Sunday.

Pakistan wrote to Swiss authorities in October over the multi-million dollar allegations against Zardari, which date back to the 1990s, at the insistence of the country's Supreme Court.