His visit however coincides with an almost unprecedented wave of repression against Iranian reformers, among them a dozen of unfortunate "loyal" dissidents accused of having accepted the invitation of German authorities to come to Berlin to explain the future of reform process initiated after the "landslide" victories of reformers in Presidential and Legislative elections in Iran.

Organised by the Heinrich Boel Institute, a pro-Green Party independent cultural foundation, the conference, held early last April and attended by 17 prominent Iranians reformers, was denounced by Iranian authorities as an "American, Zionist inspired" forum to prepare the grounds for toppling the ruling Islamic Republic.

The sentences angered the Germans, particularly the Foreign Minister Joschka Fischer, who is also the leader of the Green Party, the junior partner in Mr. Schroeder’s coalition government, and which the ruling conservative wing in Tehran described as a "Zionist" movement.

Herr Thierse visit to Tehran follows that of his Iranian counterpart Kamal Kharrazi to Berlin two weeks ago, aimed at dissipating Germany’s "concerns" over the verdicts against the participants in the Berlin, explaining that the sentences were handed down by competent courts that, according to Iranians, are "as independent as in Germany".

Informed sources said during his visit, Mr. Thierse is scheduled to meet representatives from Iranian students and Mr Ata’ollah Mohajerani, the former Culture and Islamic Guidance who was forced to resign under explicit demand from the Iranian leader, Ayatollah Ali Khameneh'i in order to "hear critical voices so he could assess the mood of the country".

Mr. Ali Afshari, an outspoken students leader is one of the participants to the Berlin meeting who was sentenced to five years prison, charged for "activities and propaganda against the Islamic Republic and insulting the leader of the regime".

"I really hope that the talks will inform me about the situation in the country and will give a differentiated picture" Herr Thierse told Berlin's InfoRadio on Friday.

He explained his visit, that take place on invitation from his Iranian counterpart Hojjatoleslam Mehdi Karrubi, saying he wanted to show his support for reformers in Iran who are fighting a backlash from conservative hardliners ahead of presidential elections due in June.

"I can't see that any kind of silence or boycott has led to any internal change in Iran", Mr. Thierse said.

Nevertheless, Iranian analysts said under present circumstances, Mr. Thierse's visit would provide hard liners a "very good pretext" to increase their offensives against reformers.

"The trip is a very good omen for the conservatives, as they would use Mr. Thierse declarations as an open interference in Iranian domestic affairs by a foreign nation", one analyst told Iran Press Service.

As a matter of fact, Iranian media, including the pro-government official news agency IRNA had not yet reported the visit, reflecting the "difficulty" the German Speaker has created for Mr. Khatami.

International League of Human Rights said in a communiqué that the visit, "at a time that reforms in Iran are undermined and reformists imprisoned" was a "wrong political move" that not only would not help Iranian reformers, but also "legalise violation of human rights in Iran".

The London-based Amnesty International called on Mr. Thierse to bring the "worsening human rights situation" in Iran with Iranian officials

Improved after Mr. Khatami’s state visit to Berlin last year, ties were again strained last month after an Islamic Revolution court in Tehran handed down heavy sentences to some of the participants in the Berlin Conference, including two translators, one of them an official working at the German Embassy in Tehran, who were not even at the meeting.

Schroeder accepted an invitation to visit Iran from Kharrazi last week, but refused to commit to a date, saying only that he would travel to Tehran when the time was right.

They also noted that an important Iranian trade delegation ended two days ago and extensive albeit unannounced and unpublicised trip to Germany, discussing with officials of several Landers, including Hamburg, Leipzig, Stuttgart and Dusseldorf ways and means of expanding economic and technical co-operation between the two sides.

Analysts said Mr. Thierse visit comes at a time that, lured by higher revenues from oil, Western industrial nations are wooing Iran more than ever.

An Italian Foreign Ministry spokesman said the trip would not be put off as that it was one of several to Iran planned by senior European officials in the coming weeks.

Amato is due to visit Tehran from February 23-25, following in the footsteps of former prime minister and current European Commission President Romano Prodi, who in 1998 became the first Western head of state to make the trip since 1979.

Iran, with around 20 percent of the world's oil reserves and around eight percent of global gas supplies, is an important potential economic partner for the West and a force in the Middle East.

The European Union has "both political and economic reasons to develop closer ties with Iran" according to a communication from the Brussels-based European Commission.

The communication, released this month, sets out perspectives and conditions for improving bilateral relations, which it says could lead to the conclusion of a Trade and Cooperation Agreement.

The recommendations in the communication are to be presented to the European Council for approval. EU Foreign Ministers are expected to discussion the proposal at their next General Affairs Council meeting on February 26-27.

"Iran could in future have a significant potential as a regional economipartner, offering substantial opportunities for trade and investment", it said.