(Reuters) - Hong Kong-based insurer AIA Group on Monday posted a 31% rise in its first-quarter value of new business (VONB) on a constant exchange currency basis and announced an additional $2 billion share buyback.

AIA's VONB, which gauges expected profits from new premiums and is a key barometer for future growth, came in at $1.33 billion in the three months ending March 31 compared with $1.05 billion a year ago.

(Reporting by Sameer Manekar in Bengaluru; Editing by Lisa Shumaker)