NEW YORK, Sept 23 (Reuters) - Weaker-than-expected economic data boosted U.S. government securities prices on Thursday and seemed to increase the likelihood the Federal Reserve would buy debt to aid the economy. An unexpected rise in new U.S. jobless claims and overnight reports showing a slower pace of growth in the euro zone's services and manufacturing sectors boosted demand for safe-haven government debt. The benchmark 10-year Treasury note US10YT=RR was up more than half a point, its yield easing to 2.50 percent from 2.57 percent late on Wednesday. The 30-year Treasury bond US30YT=RR, rose more than a point, its yield...