Japan's 10-year yield rose to a six-month high at 0.090 percent after sources told Reuters on Friday the BOJ was holding preliminary discussions on possible changes to its monetary policy.

These included adjustments to interest-rate targets and stock-buying techniques and a focus on ways to make the massive stimulus programme more sustainable.

The rare spike in Japanese yields set the tone for the start of European market trading.

Germany's 10-year bond yield rose to 0.39 percent , its highest level in around a month.

U.S. 10-year Treasury yields also touched one-month highs at 2.90 percent as the European session got under way.

"This story has got a lot of interest over the weekend, so it looks like investors are actively getting interested in what it means for JGBs," said Peter Chatwell, head of rates strategy at Mizuho in London.

"The idea that the BOJ would want to review policy, we take seriously, but this has been ongoing for some time."

Shifting market views on Japanese policy come as other major central banks move away from low interest rates and as trade relations between the United States and its major trading partners worsen.

The U.S. Federal Reserve is in the midst of a monetary policy tightening cycle, while the European Central Bank said in June that its massive stimulus scheme was set to end this year.

The ECB meets on Thursday and is likely to be pressed for more details on its plans to end quantitative easing.

Greek bond yields showed little reaction after S&P Global Ratings on Friday raised its outlook on Greece to positive from stable while affirming its B-plus/B ratings.

Last month, S&P raised its long-term debt rating on Greece, based on reduced debt risks due to the creation of cash buffers and the extension of maturity on its debts.

The country is due to exit its third international bailout next month.