Norway's annual core inflation rate rose unexpectedly in May, Statistics Norway (SSB) data showed on Wednesday, supporting expectations interest rates could increase further this year. Core inflation, which strips out changing energy prices and taxes, stood at 3.4% year-on-year, up from 3.2% in April, and above the 3.2% expected by analysts in a Reuters poll. Norges Bank had expected core inflation of 3.3%. Norway's currency, the crown, strengthened to 10.96 against the euro by 0609 GMT, from 11.00 ahead of the data release.