UPDATE 1-Fed's Lockhart sees bond buying beyond mid-2013

* U.S. central bank could also taper asset purchases

* All eyes on when quantitative easing program will end

NEW YORK, Jan 17 (Reuters) - The Federal Reserve will very likely need to continue its large-scale asset purchases into the second half of this year, since a big improvement in the U.S. labor market is unlikely to have happened by then, a top central bank official said on Thursday.

"My own sense of this is that it is probably going to be a struggle to see by mid-year a clear indication that the outlook for the labor markets are in a new phase, and it's quite optimistic," Atlanta Fed President Dennis Lockhart said at a conference hosted by Bloomberg.

"So I would tend to believe that this bond purchasing will need to continue longer into the year," he added. "Whether it goes beyond that, I think, is a question that the committee will take up in trying to weigh efficacy, costs and improvement."

To speed up the tepid U.S. economic recovery, the Fed is currently buying $45 billion worth of U.S. Treasury bonds and an additional $40 billion of mortgage-backed securities per month under its quantitative easing program, dubbed QE3.

Lockhart, a centrist monetary policymaker who does not vote on policy this year, later told reporters the Fed could taper its bond buying, and could also selectively reduce purchases of either Treasuries or MBS, when the time finally comes.