A newly painted portrait of Swedish climate activist Greta Thunberg was quickly defaced — first with a pro-oil message, and later with a slur against the teen.

The mural was painted on a section of a downtown "free wall" along a bike path that runs parallel to 109 Street near the Alberta Legislature. Local artist AJA Louden has confirmed he painted Thunberg Friday.

A CBC journalist was shooting footage of the mural on Sunday morning when James Bagnell walked up with spray paint and began painting "Stop the Lies. This is Oil Country!!!" over the teen's face.

"This is Alberta. This is oil country. My father has worked in the oil industry. We don't need foreigners coming in and telling us how to run our business, support our families, put food on our tables," he said.

Bagnell said as soon as he saw photos of the mural on social media, he decided to go down and "deal with it." He said his father, who recently died, would have been "disgusted" to see the portrait of Thunberg.

He said Canada shouldn't change its energy industry because other countries are worse offenders.

James Bagnell paints a pro-oil message over a downtown Edmonton portrait of teenage climate activist Greta Thunberg. (Gabrielle Brown/CBC)

"I think it's absolutely intolerant of them to tell us how to change our lives and our people. She should go back to her country and try to make her country better."

He said Thunberg is a child who is "doing what she's told," and doesn't know better. He said he's not against becoming more eco-friendly, but said Thunberg offers no solutions.

"Just shut up until you have solutions," he said.

Later, when CBC returned to shoot more footage, a different man was further defacing the mural — this time calling the teen a derogatory term, and telling her to get out of the country. The man declined to be interviewed.

A newly painted mural of Swedish climate activist Greta Thunberg was further defaced on Sunday morning. CBC has blurred a derogatory term that later appeared on the mural. (Andreane Williams/CBC)

'Not a big deal at all'

Reached by email Sunday after the initial pro-oil message was painted, Louden said it's normal for artists to paint over each other's work as it's a free wall.

"Nothing lasts forever — one of my favourite things about that wall is that anyone is allowed to express themselves there, so I'm not upset at all. I haven't seen what went over it, but if anyone is upset about what was painted over the portrait, they can just paint back over it, it's not a big deal at all," Louden wrote.

Mary Bjorgum, a passerby who watched the artwork go up on the wall, was also not surprised, but disappointed, she said.

"Incredibly disappointed because it was a beautiful piece of artwork, time and effort went into making it," Bjorgum said. "I appreciate that they want to express there but to actually deface it is quite another thing."

Thunberg was in Edmonton Friday to attend a climate march and rally at the Alberta Legislature that was attended by thousands of people. Her visit attracted a smaller, counter protest presence.

Thunberg then travelled to Fort McMurray, where she met with leaders of the Mikisew Cree First Nation and the Athabasca Chipewyan First Nation, as well as to participate in a BBC documentary about the region.