TOKYO, June 14 (AFP): Japanese share prices may hit volatility in the coming week after the key Nikkei index topped the 10,000 mark for the first time in eight months, dealers said Friday.

Increased optimism about the global economy and plentiful cash in the market due to easy monetary policies worldwide meant money flowed into a whole range of shares in the Tokyo stock market.

"After the Nikkei tops the 10,000 levels, the market usually takes a breather," said Seiichi Suzuki, market analyst at Tokai Tokyo Securities.

"The Japanese market in recent weeks has often been unexpectedly robust, shrugging off bad economic data," such as April machinery orders, he said.

Japanese shares closed Friday above the psychologically important 10,000 level for the first time since October, buoyed by hopes of a world economic recovery following upbeat data from the United States and China.

Japan's factory output data for April, revised up to a 5.90 per cent gain from the previous month-the fastest monthly pace in more than half a century-also helped boost shares.

Over the week to June 12, the benchmark Nikkei-225 index gained 367.81 points, or 3.77 per cent, to 10,135.82. The broader Topix index of all first section shares gained 33.98 points, or 3.71 per cent, to 950.54.

Takero Inaizumi, head of equities at Mizuho Investors Securities, said the current bullishness is not fully backed by fundamentals, expecting a Nikkei range in the coming week anywhere between 9,750 and 10,500.

"The Nikkei may become much more volatile next week," he said, referring to downside risks including US interest rate concerns and the possibility that the yen strengthens, hurting exporters.

Suzuki also said the Group of Eight finance chiefs' meeting this weekend is likely to weigh on the market, as it is expected to discuss exit strategies from stimulative policies including rate hikes.