TEHRAN Feb 21 (Reuters) - Visiting former German chancellor Gerhard Schroeder criticised on Saturday Iranian President Mahmoud Ahmadinejad for casting doubt over the Holocaust, saying the slaughter of 6 million Jews by Nazis was a fact.
Since coming to power in 2005, Ahmadinejad has provoked international condemnation for saying the Holocaust was a "myth" and calling Israel a "tumour" in the Middle East.
"The Holocaust is a historic fact and there is no sense in denying this unparalleled crime," Schroeder told the Iranian Chamber of Industry and Commerce.
"Iran needs to take responsibility and respect international rules, if it wants to be taken seriously as a regional power."
Schroeder, due to meet Ahmadinejad in Tehran later on Saturday, also criticised the hardline leader for his views on Israel which Iran has refused to recognise since its 1979 Islamic revolution.
Schroeder arrived in Tehran on Thursday for a four-day unofficial visit.
Ahmadinejad, who often rails against Israel and the West, said in January the subject of the Holocaust had been used to expand the international influence of the United States and Britain after World War Two.
Responding to Schroeder's remarks, the head of Iran's Chamber of Industry and Commerce Mohammad Nahavandian said it would be wrong to "measure the developments in the Middle East with two yardsticks".
"We shouldn't forget the recent massacre of people in the Gaza strip and should internationally condemn Israel for it," Nahavandian said.
Iran has repeatedly condemned the Jewish state's three-week offensive against Gaza earlier this year that killed 1,300 Palestinians. Ahmadinejad has described it as "genocide".
Israel, the United States and their European allies suspect Iran of trying to use its nuclear programme to build an atomic bomb. Tehran insists its nuclear work is aimed at generating electricity.
(Reporting by Parisa Hafezi, Editing by Katie Nguyen)