TOKYO, July 3 (Reuters) - Japan's Nikkei share gauge

swung between gains and losses on Thursday as uncertainty over a

trade deal with the United States and the threat of heavy

tariffs prompted investor caution.

The Nikkei 225 Index edged 0.1% lower as of the

morning break while the broader Topix was down 0.3%.

Prolonged trade negotiations with the U.S. have yet to

produce a deal, with President Donald Trump recently threatening

even higher tariffs on Japan.

Prime Minister Shigeru Ishiba said on Wednesday he was

determined to protect Japan's national interests, while chief

trade negotiator Ryosei Akazawa was reported to be organising

his eighth visit to the U.S. as early as this weekend.

"If the negotiations do not produce results, it will be a

major blow to the Japanese economy," said Nomura strategist

Fumika Shimizu.

There were 112 advancers on the Nikkei index against 110

decliners. The biggest percentage losers on the gauge were

Muji-brand retailer Ryohin Keikaku ( RYKKF ), down 6%, followed

by NH Foods ( NHFOF ), which slid 4.9%.

JFE Holdings ( JFEEF ) surged 4.9%, leading an advance among

iron and steel makers, which were the biggest gainers among the

Tokyo Stock Exchange's 33 industry sub-indexes.

(Reporting by Rocky Swift in Tokyo; Editing by Mrigank

Dhaniwala)