Japan may let more foreign workers from Asia work at construction sites under an on-the-job training system ahead of the construction boom in the run-up to the 2020 Tokyo Olympics, officials said Friday.

The Liberal Democratic Party-led government is considering relaxing a range of curbs on the entry of Vietnamese and other Asian workers to cope with the labor shortage in the construction market, they said, adding that they hope any relaxation won't lead to the exploitation of cheap foreign labor at the expense of the domestic workforce.

Measures under consideration include extending the on-the-job training period to five years from the current three.