Labour leader Alan Kelly has apologised after he was pictured not wearing a face mask while travelling on the Luas.
The Herald obtained a picture of the Tipperary TD travelling on the Green Line on Tuesday night.
In it, Mr Kelly can be seen without a face mask or other covering.
He apologised yesterday, saying he was distracted while watching Manchester United's Champions League defeat to RB Leipzig.
"I am a strong supporter of all the public health guidelines and rules and always endeavour to wear my mask where required," Mr Kelly said in a statement.
"My track record on calling for clear guidelines around mask wearing speaks for itself.
"While getting the Luas home last night, I obviously inadvertently didn't have my mask on for a period and I want to apologise for this mistake.
"I was distracted while watching the Man United match on my phone and adjusting my headphones at the same time.
"We all make mistakes. Sorry."
The picture emerged the day after Mr Kelly called on all TDs and senators to sign a Labour pledge to support the rollout of the Covid vaccine and the public awareness campaign and to take the vaccine themselves.
He has been at the forefront of Covid-19 campaigning, and in recent weeks has been challenging the Government on its plans to roll out a vaccine, including calling for a dedicated vaccine minister.
He has been a strong advocate for face masks, heavily criticising the last government for the "chronic disaster" in its communications around wearing them.
"Nobody should get on public transport without a mask, full stop. People should wear masks in retail outlets to protect workers," Mr Kelly told the Dáil in June.
In October, he said the Government needed to be clearer in calling on the public to wear masks instead of visors.
"We have to communicate the difference between visors and proper masks," he said.
"There is a huge difference. I have stressed it for a week to the Taoiseach and the Minister for Health," he said.