TOKYO, Sept 9 (Reuters) - Japan's Nikkei share average turned negative in mid-morning trade on Friday, erasing earlier gains after sentiment was soured by news of an artificial earthquake in North Korea seen as a possible nuclear test.

The Nikkei fell 0.3 percent to 16,917.22 as of 0058 GMT, after rising to as high as 17,029.78 earlier.

The U.S. Geological Survey reported a 5.3-magnitude seismic event in North Korea on Friday, near a nuclear test site in the northeastern part of the county.

(Reporting by Ayai Tomisawa; Editing by Chang-Ran Kim)