SINGAPORE, May 6 (Reuters) - The Japanese yen surged

suddenly on Wednesday, with suspected intervention last week

leading to a jump in the battered currency and traders on watch

for further moves from Tokyo authorities.

The yen was last at 156.15 per U.S. dollar, up 1%

on the day. Trading was thinned with markets in Japan closed for

a holiday. Japan's Ministry of Finance (MOF) was not immediately

available for comment when contacted by Reuters.

Investors were wary of further intervention from Japanese

authorities after sources told Reuters last week that Tokyo had

stepped in to stem the yen's decline on Thursday. Data on Friday

showed Tokyo may have spent as much as $35 billion to support

the yen.

Japanese Finance Minister Satsuki Katayama on Monday warned

against speculative moves in foreign exchange, after a brief

jolt higher in the yen at the start of the week sparked

speculation Tokyo had again intervened to support the currency.

"As I have said repeatedly, we will take decisive measures

against speculative moves, in accordance with the statement

signed between Japan and the United States last year," Katayama

told reporters after the Asian Development Bank's annual meeting

in Uzbekistan.

Traders at agent banks have been standing by to get

intervention orders throughout the holiday period, a market

source told Reuters.