Sammy Wilson said he “should have had it on and am offering no excuse”.
A photograph has been posted on Twitter of Mr Wilson on board a train, reading a magazine and not wearing a mask.
Everyone is equally subject to the law and equal under the law
Asked about the matter at the Stormont Executive press conference, Mrs Foster said: “Sammy has made a statement in relation to that matter.
“But just for clarity, I want to say this as clearly as I can, everyone is subject to the law, everyone is equally subject to the law and equal under the law.
“So it is important that we remember that, and that is the position of the DUP.”
She added at the press conference on Thursday evening that she had not had the opportunity to speak to Mr Wilson about the matter yet.
“Everybody has to abide by the law and take the consequences as well as not abiding by those laws,” she said.
Whoever took the picture didn't approach me or say anything to me which I suppose would have been the proper way to behave
In a statement, Mr Wilson queried why the person who took the photograph had not approached him directly on the train.
“I didn’t have a mask on, should have had it on and am offering no excuse but it is sad that we have now become like East Germany under the Stasi where members of the public think it is acceptable to act as snoops,” he said.
“Whoever took the picture didn’t approach me or say anything to me which I suppose would have been the proper way to behave.”
Most NI MPs do acknowledge, understand and respect rules re facemasks on London Undergroun. pic.twitter.com/poXJlYyy0Q
— Stephen Farry MP (@StephenFarryMP) September 24, 2020
North Down MP Stephen Farry tweeted: “Most NI MPs do acknowledge, understand and respect rules re facemasks” on public transport.
Those caught not wearing a mask on public transport in London can face a £200 fine, which doubles each time a person is caught, up to £6,400.
There are exemptions for the rule on the basis of age, health and disability reasons.
Earlier this week, Conservative MP Danny Kruger apologised after being spotted without a mask during a public transport journey in London.
Mr Kruger, David Cameron’s former speechwriter, said in a statement: “I boarded an almost empty carriage at Hungerford and quite simply forgot to put on my mask.
“When I got to Paddington I realised my mistake and covered up for the rest of my journey.
“If the person had reminded me rather than taking a photo and posting it on social media I would of course have put on my mask then and there.
“I do apologise for my mistake.”
Mr Wilson has previously been outspoken about the wearing of face coverings.
In July he tweeted a photograph of himself in an ice cream shop in Co Antrim not wearing a mask, with the message “you can’t eat ice cream when you’re muzzled!”
Face coverings in indoor places became compulsory in Northern Ireland on August 10th.
