TEHRAN, Iran – President Mahmoud Ahmadinejad faced a new round of sharp criticism at home Monday after he said Iran's nuclear program is an unstoppable train without brakes. Reformers and conservatives said such tough talk only inflames the West as it considers further sanctions.
The criticism came even as new signs have arisen that Iran's supreme leader Ayatollah Ali Khamenei is growing discontented with Ahmadinejad, whom he is believed to have supported in 2005 presidential elections.
Last week, Khamenei voiced rare criticism of the domestic performance of Ahmadinejad's government, and the president was notably absent when a group of Cabinet members and vice presidents met with Khamenei, who has the final word in all political affairs in Iran, including the nuclear issue.
• Monitor the nuclear showdown in FOXNews.com's Iran Center.
The increasing criticism reflects public worries about the course of the country's confrontation with the United States and the West. Washington has taken a more aggressive stance toward Iran, building up the U.S. military presence in the Gulf and accusing Tehran of backing militants in Iraq. That has hiked fears among Iranians of possible U.S. military action.
On Monday, the U.S., the four other permanent members of the Security Council and Germany met in London to consider further sanctions against Iran over its nuclear program, after Tehran rejected U.N. demands it halt its uranium enrichment program.
On the eve of the gathering, Ahmadinejad struck a defiant tone. He told a group of clerics that Iran's nuclear ambitions were unstoppable. "The train of the Iranian nation is without brakes and a rear gear ... We dismantled the reverse gear and brakes of the train and threw them away some time ago," he said.
Those comments brought a hail of condemnations in Iran on Monday, not only from reformists who have long opposed Ahmadinejad, but also from conservatives who once backed him but now see his fiery rhetoric as needlessly provoking the West into confrontation.
"Why are you speaking a language that causes a person to be ashamed?" wrote the reformist daily Etemad-e-Melli, or National Confidence.
"A train's brakes are needed to reach its destination safely," it said. "You represent the voters of the great Iranian nation. Speak equal to the name and dignity of this nation."
The conservative daily Resalat chided Ahmadinejad, saying "neither weakness nor unnecessarily offensive language is acceptable in foreign policy."
"Our foreign policy must reflect the ancient Iranian civilization and rich Islamic culture of the Iranian nation. Therefore, delicacy ... rich diplomatic language and non-primitive policies must be part of a calculated combination to work," it said.
Ahmadinejad's critics have grown more vocal ever since his allies suffered a humiliating defeat in local elections in December. That vote was swept by reformists and anti-Ahmadinejad conservatives who said the president has spent too much time castigating the West and neglected dealing with Iran's faltering economy.
The president appeared to have toned down his rhetoric in the past few weeks, insisting Iran would not give up its nuclear program but using a more moderate tone and expressing a desire to negotiate with the West.
Iranian political analyst Iraj Jamshidi said it appeared "the top leadership has cautioned him about his remarks" but Ahmadinejad's tough rhetoric "is part of his personality."
Iran denies U.S. and Western claims that it seeks to develop nuclear weapons, and the country's political factions have long been united in their stance that Iran has a right to a peaceful nuclear program. So far the criticism of Ahmadinejad has focused on his confrontational tone — though some reformers have gone further, saying Iran should be more willing to compromise in the standoff over the enrichment program.
The Islamic Iran Participation front, Iran's largest reformist party, has said Iran must return to suspension of enrichment activities to pave the way for a compromise.
Iran's nuclear policy is ultimately in the hands of Khamenei, who has always been a proponent of pushing ahead with the program. There have been no signs that he has changed that stance, but there are indications he is souring on the performance of his protege, Ahmadinejad.
On Feb. 19, Khamenei hosted a series of top officials for meetings, including several Cabinet ministers and vice presidents — but not Ahmadinejad. The same day, Khamenei — who has rarely criticized a president since he became supreme leader in 1989 — blamed the government for failing to use constitutional articles allowing privatization of state industries "to create an economic breakthrough."
At the same time, Ahmadinejad's top political rival, Ayatollah Akbar Hashemi Rafsansjani, has emerged as a high-level advocate of a more conciliatory stance toward the West, saying the nuclear dispute needs to be resolved through "dialogue and wisdom."
Rafsanjani, a top figure in Iran's clerical leadership, lost to Ahmadinejad in the 2005 election, but Rafsanjani's allies were among those swept to victory in the December local elections.
The big powers at the U.N. are considering new steps against Iran after it ignored a U.N. Security Council deadline last week to suspend uranium enrichment. Enriched to a low level, uranium is used to produce nuclear fuel but further enrichment makes it suitable for use in building an atomic bomb.
Visit FOXNews.com's Iran Center for complete coverage.