The DUP MP Sammy Wilson has been told to “wise up and “wear a mask” by his former DUP colleague in the Northern Ireland Assembly, Jimmy Spratt.
Mr Spratt, who has been undergoing cancer treatment, criticised Mr Wilson after the MP was photographed on the London tube without a face covering.
Mr Wilson admitted he was not wearing a face covering when he should have been.
Mr Spratt said he was “totally furious” about the incident and said the DUP MP needs to be “much more responsible”.
The photo of Mr Wilson using public transport without a face covering appeared on social media on Thursday morning.
Mr Wilson said he accepted he “should have been” wearing a face covering.
“I’m making no excuses and will accept whatever consequences there are, so am not going to try to justify anything,” he added.
The East Antrim MP was pictured reading a magazine, as he headed to the airport.
The man who took the photo – who asked not to be named – said Mr Wilson got on the tube at Westminster at about 08:30 BST and sat opposite him.
He claimed Mr Wilson did not wear a mask during the journey.
On Thursday, the DUP MP told the Belfast Telegraph newspaper: “I wore a mask before getting on the train, while on the train, in the airport and on the plane.
“I took a call and you can’t talk through a mask as you are muffled, so I took it off but put it back on again soon after.”
‘Stop the stunts’
Mr Spratt criticised Mr Wilson on Twitter, saying it was time for him to “grow up and wise up and do the right thing and stop the stunts”.
Speaking to BBC NI’s Good Morning Ulster about the tweet, the retired MLA said: “I was just totally furious, because it’s not the first time Sammy has done a stunt.
“But I feel he needs to be much more responsible and to toe the line and do the right thing and try and protect everyone, if he doesn’t want to protect himself.”
Jimmy Spratt and Sammy Wilson are both former DUP members of the Northern Ireland Assembly (MLAs).
Mr Spratt represented the South Belfast constituency from 2007 until he retired on health grounds in 2015.
At the time he spoke publicly about undergoing treatment for bowel cancer and said his health “must take precedence over the unrelenting nature of an MLA’s schedule”.
British Transport Police
Transport for London (TfL) says those caught not wearing a face covering on its services could face a minimum fine of £200, which doubles each time a person is caught, up to £6,400.
Exemptions apply for age, health and disability reasons and TfL provides an “exemption card” for those unable to wear one.
The witness told BBC News NI he had been contacted by the Met Police who said they had passed on the case to the British Transport Police.
When asked about the photo on Thursday, DUP leader Arlene Foster said that “everyone is subject to the law and everybody is equal under the law”.
“Therefore it is very important that we listen to the laws and abide by them,” she said.
Mr Wilson has previously criticised the rules around wearing face masks.
In July, before face coverings in shops became mandatory, he posed on Twitter at an ice cream parlour in Islandmagee, County Antrim.
His message was “Support Local Business” and he went on to point out that “you can’t eat ice cream when you’re muzzled!”