Moody's Investors Service yesterday surprised bond markets by raising the outlook on its credit ratings for Russia from stable to positive, citing the oil-rich country's strong economy.

Moody's rates Russia at the lowest investment grade category of Baa3, one notch higher than either Standard & Poor's or Fitch Ratings, which have Russia in the highest junk grade. A positive outlook means that the next move in the rating is likely to be up.