Saskatchewan Premier Brad Wall is apologizing after retweeting a Twitter post that referred to Prime Minister Justin Trudeau with the word "shithead".

It happened Tuesday after Wall was on social media criticizing Trudeau's carbon pricing plan.

Ottawa proposes that the price on carbon pollution should start at a minimum of $10 per tonne in 2018, rising by $10 each year to $50 per tonne in 2022.

Wall calls it a tax that will kill jobs and cause serious harm to Saskatchewan's most important industries. Trudeau has argued that any revenue collected through carbon pricing will stay in Saskatchewan.

Wall retweeted a tweet from someone named "Branik Fedikov" —who uses the Twitter handle "Libslikdik" — that said this: "@Andrew_Dalgarno @PremierBradWall @JustinTrudeau if all the money goes back why take it in the first place #shithead".

The retweet was public for more than half an hour, according to the timestamp, before Wall deleted the tweet. Hours after that, he apologized.

Brad Wall retweeted a Twitter post referring to Justin Trudeau's carbon pricing plan that included a profanity. (Twitter)

"Earlier I retweeted a post re carb tax w/ a profane hashtag ref the PM that I simply didn't initially see. Minutes later it was deleted," Wall said on his Twitter account.

"I should have been more careful and apologize. No doubt the debate on the carbon tax will be lively but it need not involve insults."

Athough Wall deleted his retweet, some people on Twitter saved the image and reposted it.