Major trading house Itochu said on Thursday that it will recall cloth face masks and tighten inspections of them following reports of defects in masks the government has delivered to households, although it is not known if Itochu's products were among those tainted.

The government's effort to distribute protective cloth masks in its coronavirus battle has been marred by complaints about mould, insects, and stains, fueling further concern that the government has botched its handling of the pandemic.

Just days after it began supplying every household with two washable, reusable masks at a cost of $430 million in the strategy to contain the virus, the government has been forced to replace some masks because of the complaints.

The health ministry has asked three companies, Kowa, Itochu and Matsuoka Corp. to manufacture masks, but it does not know whose masks were defective, a ministry official said.

"We have requested all three companies to tighten inspections of masks," he said.

Itochu will recall masks that have not been distributed and reinforce inspections by making triple checks on all products to respond to the ministry's request, it said in a statement.

Kowa and Matsuoka were not immediately available for comment.

Japan has seen more than 11,500 infections and close to 300 deaths from the new coronavirus.

The pandemic has caused a shortage of masks in Japan, where the items fashioned from paper or cloth are a common sight, particularly in winter and spring.

Electronics maker Sharp has halted online sales of masks after overwhelming demand crashed its website soon after it began taking orders on Tuesday.

Sharp said on Thursday it will sell the masks through a lottery instead to avoid more crashes. The first lottery will be held on April 28.