KIEV, Aug. 31 - Standard & Poor's Ratings Services said Thursday it has affirmed its 'BB-' long-term foreign, 'BB' long-term local, and 'B' short-term sovereign credit ratings for Ukraine, as the economy continues to outperform expectations and the political environment has stabilized.

The outlook is stable, the credit rating agency said.

"Despite a drawn-out political crisis since the March 2006 elections and the doubling of natural gas import prices earlier in the year, the Ukrainian economy has outperformed expectations," said Standard & Poor's credit analyst Moritz Kraemer in the press release.