WASHINGTON – An Iranian prosecutor who is accused of condoning the torture, rape, and murder of a Canadian photojournalist will have to plan his trips to Europe and the Americas carefully after it was disclosed that the Canadian government is now demanding his arrest if he leaves Iran.

The Canadian foreign minister, Peter MacKay, telephoned his German counterpart last week and asked that Saeed Mortazavi be arrested if he set foot in Frankfurt, Germany. Mr. Mortazavi was expected to stop over in the German city on his flight back to Tehran from Geneva, Switzerland, after attending the opening session of the new U.N. Human Rights Council.

The Canadian government has declared that Mr. Mortazavi’s 2003 decision to send photographer Zahra Kazemi, a Canadian citizen, to the prison where she was murdered makes him culpable in the crime.

Speaking to reporters in Ottawa, Prime Minister Harper said on Friday that he was making an appeal to the world to use “all manner of law” available to apprehend Mr. Mortazavi. Mr. MacKay was even stronger in his wording, telling reporters Thursday night: “Mark my words, this individual is on notice. If there is any way Canada can bring this person to justice, we’ll do it.”

The move from Canada to appeal for the arrest of Mr. Mortazavi could provide a window into what Western diplomacy toward Iran might look like should the ruling mullahs spurn an offer to negotiate an end to their enrichment of uranium.

In January, American diplomats began meeting with their European counterparts to devise sanctions against the regime that would not be contingent on the approval of a divided U.N. Security Council. While that track appears to have been put aside for now in favor of inducing Iran to negotiate on its nuclear program, last week the national security adviser, Stephen Hadley, set a soft deadline of this week for an Iranian response to the negotiation offer. President Ahmadinejad said he would need until August.

According to a dispatch filed over the weekend on Radio Farda, the American-funded Persian radio station, Mr. Mortazavi was displeased by the international reaction to his participation in the Iranian delegation to Geneva, particularly that the human rights group, headed by a Nobel Peace Prize winner, Shirin Ebadi, appealed against the prosecutor’s presence in a letter to U.N. Secretary-General Annan.

On Saturday, Iran’s foreign minister responded to the Canadian campaign with invective. “The Canadian claims are illogical and they should understand who they are talking to and they should speak up to their level,” Manouchehr Mottaki told Iran’s official news agency from Geneva on Saturday.