This is the fifth straight month the company kept prices unchanged for all of its steel products, including its main H-shaped beams.

For May, prices of steel bars, including rebar, will remain at 69,000 yen ($617) a tonne, while H-shaped beams will also stay at 89,000 yen a tonne.

"Local flow of steel products have slowed as a shortage of some materials such as bolts caused delays in some construction projects, while higher imports also helped boost local steel inventories," Tokyo Steel Managing Director Kiyoshi Imamura told reporters at a briefing.

"But I expect bolts shortage to ease and construction activities will pick up by end-June as domestic demand is fairly strong due to redevelopment projects in Tokyo metropolitan area and construction of new hotels in Okinawa, Kyushu and Hokkaido to meet rising foreign tourists," he said.

Tokyo Steel's pricing is closely watched by Asian rivals such as South Korea's Posco and Hyundai Steel, and China's Baoshan Iron & Steel Co Ltd (Baosteel)