Japan's barriers to foreign labor are showing signs of cracking as preparations for the 2020 Tokyo Olympics threaten to exacerbate the worst shortage of construction workers in almost 20 years.

Curbs on visas for foreign blue-collar workers may be loosened, Chief Cabinet Secretary Yoshihide Suga said Friday. More than 25,000 laborers will be needed for stadiums, arenas and other Olympics facilities, Tokyo's government estimates, adding to demand from earthquake and tsunami rebuilding.

Japan's shrinking population may pressure Prime Minister Shinzo Abe to open the door wider to workers from abroad as part of his drive to sustain a revival of the world's third-biggest economy. Abe is up against a culture that has valued homogeneity, with foreigners accounting for only about 1 percent of the labor force, compared with 36 percent in Singapore.