SoftBank founder Masayoshi Son on Thursday tweeted an offer to donate a million free face masks to help fight the coronavirus outbreak a day after twitter users criticized his proposal to give away test kits as an unnecessary burden on clinics and hospitals.

"I will donate a million masks," Son tweeted in reply to a suggestion from one person, who identified themselves as a dentist in Kobe western Japan.

The coronavirus pandemic has prompted The SoftBank Group chief executive, who has 2.4 million followers, to begin tweeting after a three-year hiatus from the social network.

The coronavirus has infected more than 126,000 people and killed 4,624, according to a Reuters tally.

Almost 1,400 of those cases are in Japan, where 22 people have died, according to public broadcaster NHK.