"The Islamic Republic of Iran is fundamentally opposed to the atomic bomb and weapons of mass destruction," Ahmadinejad told Hatoyama.

"Iran and Japan can exert a common effort to create a world without atomic weapons ... Difficult but humanitarian efforts will win in the end."

Japan is the only country ever to have suffered a nuclear attack, its cities of Hiroshima and Nagasaki being targeted by the United States at the end of World War II.

Hatoyama's presence in Iran was an issue of contention in Japan, after Japanese Foreign Minister Koichiro Genba reportedly requested he not make the trip.

Prime Minister Yoshihiko Nodahe has also expressed concerns over Hatoyama's visit, fearing it could undermine the Japanese government's efforts for international coordination, Japanese media reported.

The visit came at a tense time, with Iran facing off against much of the West over its nuclear programme.

The United States and its allies fear Iran is seeking nuclear weapons capability, something Tehran denies.

Talks between Iran and the five permanent UN Security Council members and Germany are due to be held starting Friday, in a country yet to be agreed.

Hatoyama was quoted as telling Ahmadinejad: "International trust-building and respecting regulations are important part of the world community which should be seriously pursued."

Ahmadinejad said Iran was "ready for negotiations" and had unspecified "practical suggestions for the upcoming meeting."

"Interior Minister Eli Yishai declared Gunter Grass persona non grata in Israel," a statement from Yishai's office said.

"Gunter's poem is an attempt to fan the flames of hate against the state of Israel and the Israeli people," it quoted Yishai as saying.

In his poem "What must be said," the 84-year-old longtime leftist activist wrote of his concern that Israel "could wipe out the Iranian people" with a "first strike" due to the threat it sees in Tehran's disputed nuclear programme.

"Why do I only say now, aged and with my last ink: the atomic power Israel is endangering the already fragile world peace?" reads the poem, which was published on Wednesday in the daily Sueddeutsche Zeitung.

The poem sparked outrage in Israel, with officials from Prime Minister Benjamin Netanyahu on down criticising Grass. Netanyahu on Thursday called Grass's poem "shameful."

"If Gunter wants to continue disseminating his distorted and mendacious works I advise him to do it from Iran where he will find a supportive audience," Yishai said on Sunday.

Israel's Foreign Minister Avigdor Lieberman also criticised the poem on Sunday, during a meeting with Italian Prime Minister Mario Monti.

He said it was an expression of the "cynicism" of some Western intellectuals, "who for their self-promotion and desire to sell a few more books are willing to sacrifice the Jewish people for the second time on the alter of deranged anti-Semites."

"We expect the European leadership to take a firm stance against such remarks made by public opinion leaders, and to not enable them," he added, warning that "we have already seen in the past how small seeds of anti-Semitic hate turn to a large fire that harms all humanity."

The poem has also sparked debate in Germany, where Foreign Minister Guido Westerwelle on Sunday penned a commentary that appeared to criticise Grass, without making explicit reference to the author.

"Germany has a historic responsibility for the citizens of Israel," he wrote in Bild Am Sonntag, Bild newspaper's Sunday magazine.

"To put Iran and Israel on an equal moral footing is not clever but absurd," he wrote.

Iran's deputy culture minister Javad Shamaqdari on Saturday praised Grass's poem, saying "it warns beautifully."

Grass, author of the renowned anti-war novel "The Tin Drum," sparked outrage in 2006 when he revealed, six decades after World War II, that he had been a member of the notorious Waffen SS.

Israel, the sole if undeclared nuclear power in the Middle East, has said it is keeping all options open for responding to Iran's nuclear programme, which it says is aimed at securing nuclear weapons, posing an existential threat to the Jewish state.

Iran has consistently denied that its sensitive nuclear work is aimed at making weapons.