Steve Kirsch, who has promoted misinformation about Covid-19 vaccines throughout the pandemic, said he “explained they (masks) don’t work” to his seatmate who apparently worked for a pharmaceutical company.

He tweeted the story while apparently on board the Delta flight, and said he started by offering her $100 and worked up.

She reportedly rejected his offer, but Mr Kirsch continued to harass the woman about her mask, even pointing out that if she removed the mask to eat and drink, “she could be infected with one breath”.

“She took off her mask as soon as the breakfast was served,” he wrote.

“Because everyone knows you can’t get infected while you’re eating!

“Maybe next time I’ll sit next to someone who had an account at Silicon Valley Bank.”

Backlash to the entrepreneur’s story came thick and fast, with many pointing out how strange it was for him to harass the woman to take his money to “remove coverings” from her body.

“Ew. Do you make a habit of offering money to random women to remove coverings from their bodies mid-air?” former Democrat state representative nominee Jess Piper wrote.

“Stop bugging people who are minding their own business with your creepy nonsense,” infectious disease expert Alastair McAlpine said.

“All you’re doing here is admitting you patronised and harassed a woman who made a decision she thought was best for her,” another user wrote.

“Way to own yourself on here, man.”

This is not the first time that Mr Kirsch has tried to pull some kind of mid-air bribery stunt.

Last week he was flying on another airline, Southwest, and tweeted that he offered his seatmates $10,000 if they would remove their masks for the flight. They also declined his offer, and he said he may offer a higher amount “next time”.

“Maybe I should offer $100,000 next time? This can quantify the amount of brainwashing,” he tweeted.

The millionaire also has a history of claiming to be trying to help with the Covid-19 pandemic, but has been linked to spreading a variety of misinformation about masks and vaccines.

American federal law no longer requires masks be worn in airports or on planes, but certain cities and states may still require them at airports.

Delta Airlines said masks are optional for customers and employees for domestic and international travel, except where required by “applicable governments” – which may include requiring masks on-board or in the airport gate or lounges.

“If this is the case, Delta will make an announcement at the gate and on board and may also place signage in the areas where masks are required,” Delta noted on its website.

International travellers are also asked to “continue to bring a mask with you” just in case.

Southwest’s website says passengers are “always welcome to wear a mask while travelling if you prefer to”.

Australian mask mandates changed in September 2022, after the national cabinet agreed to ditch the mask rule for domestic travel.

In June 2022, face masks became optional in airports and, that same month, Qantas lifted its in-flight mask requirements for outbound international routes where masks are not required by the government of the destination.

And while there is some debate over the effectiveness of face masks, the prevailing attitude in these Covid-normal, post-pandemic times is to wear them if you want to.

A recent Cochrane Review – considered the gold standard of evidence-based medicine – concluded that “wearing masks in the community probably makes little or no difference” in an effort to prevent Covid-19.