In a statement on Sunday, Steinmeier expressed concerns about the trial of more than 100 people accused of violence during mass demonstrations following disputed elections in June.

"The reports about the beginning of the trial of members of the opposition in Iran deeply concern us," Steinmeier said.

"The Iranian government is called on to release the political prisoners and respect international standards for the protection of civil and political rights of its citizens to which it has agreed."

More than 100 people went on trial on Saturday in Iran, including several leading reformists, on charges including rioting, vandalism, and conspiracy against the government.

Berlin is "deeply concerned"

Steinmeier said the government in Berlin had reason to believe the people brought before a revolutionary court in Tehran would not have a "transparent or fair trial."

Leading moderates say the vote was rigged in favor of the current president. The authorities deny the charge accusing the West of instigating the protests.

At least 20 protesters were killed and more than 1,000 were arrested in the biggest internal crisis to hit Iran since the 1979 Islamic revolution. Most of the people taken into custody have been released, though there are still around 250 in jail.

"The exact number of political prisoners in prison who were arrested after the disputed presidential election on June 12 is unknown but their number is estimated at several hundred," Steinmeier said.

"In addition, there are the several political prisoners who were already arrested in recent years."

Mousavi accuses regime of torture

Iran's leading opposition figure and defeated presidential candidate, Mir Hossein Mousavi on Sunday accused the regime in Tehran of torturing the detained activists to get confessions.

In a statement on his Web site, he said "the torturers and confession-makers have brought the issue to a point where their victims are among those who have remarkably served this country and the system."

Among those standing for trial in Tehran are many former officials and politicians.

Mousavi accused the interrogation of "medieval torture" to force the arrested to make confessions over the post-election unrest.

He rejected the accusation that the demonstrators had been pushing to overthrow the government in a revolution. Mousavi said the people were only "seeking freedom and justice."

Former Iranian President Mohammed Khatami has criticized the trial as a "show trial", saying it violated the constitution and would damage confidence in Iran's government.

"The trial on Saturday was a show and the confessions are invalid ... What was called a trial was a violation of the constitution," a statement on his website said. "Such show trials will directly harm the system and will further damage public trust."

ai/AFP/AP/EPD
Editor: Sonia Phalnikar