Canada's ambassador to Iran has been expelled from Tehran, Foreign Affairs Minister Maxime Bernier said Monday.

"Canada regrets the decision of the Government of Iran to order our ambassador to leave Tehran, which is entirely unjustifiable," Bernier said in a news release.

The expulsion is believed to have stemmed from the two countries not being able to come to an agreement over an exchange of ambassador candidates, he said in the release.

"Canada and Iran have tried to come to an agreement on an exchange of ambassadors for some time. Unfortunately, we have as yet been unable to accept the candidates Tehran has submitted. We believe that the expulsion of our ambassador is an unfortunate and unjustified consequence of this situation," reads the release.

"The Canadian Embassy in Iran will be headed by our charge d'affaires who will represent and safeguard Canada's interests. Both countries will continue to maintain embassies in the respective capitals and conduct normal operations," it says.

"We strive to keep our lines of communication open ... As always, Canada remains prepared to receive an Iranian ambassador provided a suitable candidate is presented," says the release.