Iran on Sunday said it was willing to help Washington calm the escalating sectarian violence in neighboring Iraq if the U.S. dropped its "bullying" policy toward the Islamic nation but denied that it had organized a summit in Tehran with Iraq's and Syria's leaders.

Hardline President Mahmoud Ahmadinejad said Iran was "ready to help" the United States, saying the White House was "trapped in a quagmire" in Iraq.

"The Iranian nation is ready to help you to get out of the quagmire — on condition that you resume behaving in a just manner and avoid bullying and invading," he said while addressing members of the Basij paramilitary group, which is affiliated with the elite Revolutionary Guard.

But the United States, which is under increased pressure at home and abroad to approach Iran and Syria for help with Iraq, disregarded Ahmadinejad's offer. Engaging with Iraq's neighbors is believed to be one of the recommendations by a panel on Iraq led by former U.S. Secretary of State James A. Baker III.

"The Iranians have made comments similar to this in the past. There's nothing new there," said U.S. State Department spokeswoman Julie Reside in Washington.

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Back in Tehran, Foreign Ministry spokesman Mohammed Ali Hosseini said a summit involving Iraq and Syria was never on Iran's agenda.

"Such a summit needs certain preliminaries," he added, but did not give details.

Iraqi President Jalal Talabani was scheduled to visit Tehran on Saturday, but had to postpone his trip until Baghdad's airport — closed in a security clampdown after a recent upsurge in violence — reopens. Syria never said whether President Bashar Assad had intended to go.

But Hosseini said Iran has invited Assad for an official visit to Tehran and confirmed that Talabani would visit Iran, though he did not say when.

Iran is believed to back Iraqi Shiite militias blamed in sectarian killings that have killed thousands this year. Iran has repeatedly denied the charges.

Had the summit been held, it would have preceded U.S. President George W. Bush scheduled meeting with Iraqi Prime Minister Nouri al-Maliki in Jordan on Wednesday and Thursday. Vice President Dick Cheney was in Saudi Arabia, a U.S. ally and another one of Iraq's neighbors, over the weekend. The unusual succession of trips appears to reflect U.S. determination to rally allies at a time when Washington is considering changing its Iraq policy.

But one of the major sources of tension between Tehran and Washington — Iran's contentious nuclear program — appears remains at a standstill. The U.S. alleges Iran is secretly developing atomic weapons, though Tehran has repeatedly claimed its program is for peaceful purposes including generating electricity.

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Iran has repeatedly refused to suspend uranium enrichment, defying an August U.N. Security Council deadline and has said it will not halt the process as a precondition to negotiations over its nuclear program.

Hosseini on Sunday promised improved cooperation with the International Atomic Energy Agency if the U.N. nuclear watchdog, rather than the Security Council, takes charge of Iran's nuclear dossier. Iran has made similar promises in the past.

"If the case is returned to the agency itself, it would be possible to review current ambiguities better than before," Hosseini said. "The agency is the best and the most qualified body for the case."

The IAEA officially turned over Iran's dossier to the Security Council in February after Iran had failed to answer key questions about its nuclear activities.

Last week, the IAEA rejected Iran's request for assistance building a heavy water reactor, which foregoes the uranium enrichment process. Enriched to a low level, uranium can be used to fuel a reactor, but enriching it further makes it suitable for a nuclear weapon.

"It is part of the agency's duties to help member countries. None of our activities have been illegal. Inspectors can inspect them," he said.

The U.N. Security Council, meanwhile, is deadlocked over how to sanction Iran for ignoring demands to stop uranium enrichment. Russia and China, both trade partners with Iran, have said repeatedly that the prefer the impasse to be resolved diplomatically rather than through imposing punitive measures, which Washington is urging.