Question on MERGE in postgresql

Greeting all,
I am using postgresql 9.4. When I try to use "Merge" command, seems not
working.

Below is the SQL statement I used. Even after I removed the business logic
part for debugging purpose, it dose not work.

MERGE INTO util.comment C
USING util.comment_orig B
ON C.jl_id_per_book = B.jl_id_per_book
WHEN MATCHED DO NOTHING;

ERROR: syntax error at or near "MERGE"
LINE 2: MERGE INTO util.comment C
^
********** Error **********

ERROR: syntax error at or near "MERGE"
SQL state: 42601
Character: 8

Any help is appreciated!

Thanks and Regards
Kalees.