U.S. Treasuries hold gains after Philly Fed data

NEW YORK, Nov 20 (Reuters) - U.S. government debt prices held their earlier gains on Thursday near their session highs, after a surprise decline in Philadelphia Federal Reserve's index on business activity in the Mid-Atlantic region.

The price on benchmark 10-year notes <US10YT=RR> traded up 1-21/32, compared with a 1-10/32 gain shortly before regional Fed data.

The 10-year yield, which moves inversely to price, was 3.15 percent, the lowest level in 5-1/2 years compared with 3.19 percent before the Philly Fed data and 3.34 percent late on Wednesday.

(Reporting by Richard Leong; Editing by Theodore d'Afflisio)