NEW YORK, Aug. 11 (Xinhua) -- The U.S. dollar traded mixed on Wednesday as investors were worried about debt problems in the U.S. and Europe, and rumors about possible downgrading of France's triple-A credit rating weighed on the euro.

After the first-ever downgrade of U.S. credit rating, there had been rumors in the markets that rating agencies might downgrade France's AAA credit rating, which raised investors' concerns about European countries' debt problems and pressured the euro.

The euro tumbled against the dollar on Wednesday. The dollar index gained 0.16 percent on Wednesday.

Meanwhile, as the markets went through huge turbulences these days, safer investments were favored by investors. Swiss franc and Japanese yen are regarded as safe-haven currencies and rose significantly against the dollar recently.

Swiss francs snapped its winning streak against the dollar on Wednesday after Switzerland's central bank said it will take measures to curb the strength of the local currency.

The British pound continued to decline against the dollar after the Bank of England trimmed its forecast for both growth and inflation.

In late Wednesday trading, the dollar bought 76.83 yen, comparing with 77.01 from late Tuesday, and the euro fell to 1. 4208 dollars from 1.4222.

The British pound also fell to 1.6160 dollars from 1.6220. The dollar rose from 0.7141 Swiss francs to 0.7296, but fell to 0.9906 Canadian dollars from 0.9938.