Iran has rejected Canadian demands that its diplomats observe the trial of an an intelligent agent charged with beating a Canadian journalist to death.
Kazemi died from head injuries sustained during her interrogation
Canada has withdrawn its ambassador to Tehran, saying "justice will not be done behind closed doors".
Iran's Foreign Ministry spokesman Hamid Reza Asefi said the case was a domestic issue, but pledged a fair trial.
Iranian-born journalist Zahra Kazemi died in 2003 after she was held for taking pictures outside a Tehran jail.
The trial had been delayed to allow lawyers representing the Kazemi family to research the case.
Iranian intelligence agent Mohammad Reza Aghdam Ahmadi pleaded not guilty to "semi-intentional murder" at the trial's first and only session last October.
"The request for the presence of Canadian observers is
contrary to all international principles and regulations and is unacceptable," Mr Asefi said on state television.
But Canadian Foreign Minister Bill Graham decried Iran's "completely unacceptable behaviour", and said he was recalling the ambassador to Tehran.
He said Canada had been promised it could have three observers at the trial.
"It's a complete rejection of the rule of law... justice
will not be done behind closed doors in Iran," he said.
Ms Kazemi, 54, was detained on 23 June 2003 for taking pictures of Tehran's Evin prison.
She died in hospital in Tehran on 10 July after falling into a coma having received head injuries during more than three days of interrogation.
The case has sparked a fierce debate between the hardline judiciary and the reformist intelligence ministry.
Both sides have accused one another of staging a cover-up to divert responsibility for Ms Kazemi's death.
The moderate President Mohammad Khatami has backed the intelligence ministry, saying: "I believe the agent was not guilty. I hope the court will bravely be able to identify the guilty person."