* Nikkei once above forecast price of futures and options settlement
* Nikkei flat for the week
* Mining shares outperform
By Ayai Tomisawa
TOKYO, Sept 9 (Reuters) - Japan's Nikkei share average edged down in choppy trade on Friday morning, erasing earlier gains following a suspected North Korean nuclear test.
The Nikkei fell 0.3 percent from the previous close to 16,913.99 in midmorning trade, after rising to as high as 17,029.78 earlier.
In early trade, Nikkei futures and options contracts expiring in September were forecast to settle at 17,011.77.
A seismic tremor was recorded on Friday in an area around North Korea's known nuclear site, and was suspected to be the fifth nuclear test by the isolated nation, South Korea's Yonhap news agency said.
A South Korean government official said it was a suspected nuclear test, Yonhap reported, and Seoul called for an emergency National Security Council meeting.
"With U.S. stocks lower and no fresh catalysts to buy, trading was subdued anyway, but the North Korea news has made investors stay on the sidelines even more," said Yutaka Miura, a senior technical analyst at Mizuho Securities.
For the week, the Nikkei was flat.
Japanese stocks have been trading in a tight range in recent weeks as investors try to assess the outlook for U.S. interest rates and the Bank Of Japan's monetary policy.
"Since many of the U.S. August economic data were poor, investors are cautiously focused on September figures," said Hikaru Sato, a senior technical analyst at Daiwa Securities.
On Friday, exporters were mixed, with Honda Motor Co falling 1.2 percent, Panasonic Corp shedding 0.2 percent and Advantest Corp rising 0.1 percent.
Mining shares outperformed, with Inpex Corp rising 3.2 percent and Japan Petroleum Exploration Co advancing 1.8 percent after oil prices soared more than 4 percent overnight.
The broader Topix declined 0.4 percent to 1,341.08 and the JPX-Nikkei Index 400 shed 0.3 percent to 12,029.67.
Editing by Simon Cameron-Moore