OTTAWA - Foreign Affairs Minister Lawrence Cannon says he's worried that Iran's investigation of detained dissenters is in the hands of an official linked to the death of a Canadian journalist.

The minister says Saaed Mortazavi has repeatedly demonstrated his disregard for human rights.

Formal investigations have tied him to the arrest, torture and murder of Canadian photojournalist Zahra Kazemi in 2003.

Mortazavi is a former judge and one of Iran's most feared prosecutors, known for shutting down newspapers and websites, and jailing journalists and bloggers.

The Iranian regime has put him in charge of interrogating people arrested in the aftermath of the country's much-challenged election.

Cannon repeated Canada's call for the release of imprisoned dissidents in Iran.

"We are deeply concerned by reports that Saaed Mortazavi has been put in charge of the investigation of detained reformist leaders and party officials in Iran," Cannon said in a statement Thursday.

"On several occasions, most notably the detention and murder of a Canadian journalist, Mr. Mortazavi has clearly demonstrated his disregard for human rights and fundamental freedoms."

The minister said two official Iranian investigations confirmed that Mortazavi ordered the illegal arrest and detention of Kazemi.

"There have also been reports that Mr. Mortazavi falsified documents to cover up his involvement in her case."

He said Canada has no intention of getting involved in internal matters in Iran, but wants to uphold international human-rights obligations.

"Canada will continue to call for the release of all political prisoners and journalists -- including Canadians -- who have been unjustly detained following the Iranian presidential elections."

A spokeswoman for Cannon also said Thursday that Iranian diplomats in Ottawa have been "disinvited" to Canada Day festivities in the capital next week.

On Friday, union officials and human-rights activists plan a demonstration in front of the Iranian embassy in Ottawa.