Stockholm - The European Union sharpened its criticism of Iran's mass trial of alleged dissidents Sunday, with Swedish Foreign Minister Carl Bildt saying that the trials were a challenge to the whole of the EU.

In an interview with the TT news agency in Sweden, which holds the rotating EU presidency, Bildt said that the proceedings in Tehran were a "show trial."

On Saturday, the second hearing in the trial focused on Iranian staff at the British and French embassies in Tehran, as well as a French citizen, charged with spying and involvement in protests in the wake of President Mahmoud Ahmadinejad's disputed re-election on June 12.

Bildt said that the EU "must be very clear" on demanding the immediate release of the accused. The situation in Tehran was "insecure," he said, and required caution.(dpa)