Two days after Mahmoud Ahmadinejad, the Iranian president, called the Holocaust a "myth", Europe's foreign ministers were expected to discuss his comments on Thursday at the EU summit.
Frank-Walter Steinmeier, the German foreign minister, said his delegation would demand an EU condemnation.
"The government in Tehran must understand that the patience of the international community is not endless," he told the German parliament in Berlin before departing for Belgium on Thursday.
Ahmadinejad first provoked an international outcry in October when he called for Israel to be "wiped off the map".
Then, on Wednesday, he said in remarks carried live by state-run television in Iran that the Holocaust was a "myth" that the Europeans used to create a Jewish state in the heart of the Islamic world.
"Today, they have created a myth in the name of the Holocaust and consider it to be above God, religion and the prophets," he said.
Nations from Europe to Asia condemned his remarks on Thursday.
Benita Ferrero-Waldner, external relations commissioner for the EU, called Ahmadinejad's views "absolutely irresponsible". Denying the Holocaust - in which more than six million Jews died during World War II at Nazi hands - is a crime in several European nations.
"Iran's participation is endangered if the president continues to express himself in this unbearable manner"
China, which maintains good relations with Iran and Israel, said such comments could undermine world stability.
Qin Gang, a spokemsn for the Foreign Ministry, said: "We are not in favour of any remarks detrimental to stability and peace. Israel is a sovereign state."
Moscow did not directly criticise Ahmadinejad but condemned any attempts to deny the Holocaust, and said it was necessary to restate Moscow's "principled position".
"Speculation on these themes runs contrary to the principles of the UN Charter and the opinion of the world community," it said.
Meir Litvak, an Iran expert at Tel Aviv University in Israel, said the president's comments reflected his true ideology.
"These statements show that Iran is led by people who are narrow-minded and dangerous in the way they perceive the world."
Steinmeier said Ahmadinejad's comments weighed heavily on talks over Tehran's disputed nuclear programme and showed "with how much irresponsibility and cynicism the Iranian government currently regards the situation of Israel and the Near East".
The EU is trying to limit Iran's
Envoys from Germany, France and Britain, who have been leading diplomatic efforts to allay fears over Iran's nuclear intentions, are to resume negotiations with Tehran on 21 December.
Some German politicians urged the government to consider excluding Iran from the World Cup soccer tournament to take place in Germany next year.
Swen Schulz, a social democrat, was quoted in the Bild newspaper as saying: "Iran's participation is endangered if the president continues to express himself in this unbearable manner."
Volker Beck, of the opposition Green party, said on German's N24 television: "The government must work at all levels to isolate Iran politically. It's worthwhile to continue the discussion on whether to exclude Iran from the World Cup."