UPDATE 5-Tokyo bourse rejects calls for halt, to keep markets open

TOKYO/NEW YORK, March 17 (Reuters) - The Tokyo Stock Exchange and Japanese financial regulators plan to keep markets open despite a report that some foreign financial institutions are calling for Japan's stock market to halt trading.

The Nikkei news agency said officials from more than 10 non-Japanese financial firms held a conference call on Tuesday afternoon to discuss the situation in Japan, where markets have been rocked by an earthquake, tsunami and nuclear disaster over the past week.

Some participants called for the market to be closed immediately, Nikkei reported, citing people familiar with the discussion.

The report said that foreign firms were looking for a trading halt because the "market was experiencing too much volatility," but did not elaborate.

The exchange plans no changes to its day-to-day operations, Tokyo Stock Exchange spokeswoman Yukari Hozumi told Reuters on Thursday.

"We are open as normal today, and will be tomorrow. We have absolutely no plan to shorten hours or halt trading," Hozumi added.

Japan's stock market tumbled in the first two days of trading after an earthquake, tsunami and nuclear disaster rocked the country. But on Wednesday, stocks soared on record volumes, despite persistent worries about overheated nuclear reactors and high radiation levels.

The benchmark Nikkei index was down 2.2 percent in mid-morning trading on Thursday.

Mike Cahill, who runs OCC, the U.S. clearinghouse for stock options, said banks might urge the TSE to close down operations if they were understaffed. Reuters has reported that foreign bank employees were racing to leave Japan due to safety concerns.

Yet representatives of several U.S. and European banks said they were unaware of any calls to halt trading activity. They noted that much of their trading and brokerage operations are performed online, allowing employees to perform trades on the TSE from off-site locations, such as Hong Kong.

HSBC said "it is business as usual" in Japan," adding that "offices and branches in Tokyo, Osaka, Nagoya and Yokohama have remained open for business."

Representatives for other large, non-Japanese banks also said evoked similar sentiments.