Reformist allies of Iranian President Mohammad Khatami said powerful hard-liners have grown increasingly anxious about the possibility of an American-led transitional government in Iraq.
"Hard-liners want to provoke the United States against Iran," a senior Iranian official said. "If the Americans start seriously threatening Iran, that gives them an excuse to crush reforms."
Iran already has begun to take steps to exert political and possibly military influence in Iraq by focusing on exiled Iraqis based in Iran.
Concerned that its sway over two leading Iraqi opposition groups is insufficient, Tehran is providing cash and arms to members who break away, opposition sources say.
Those who have split from the ranks of the two main Shiite groups opposed to Saddam Hussein's regime -- the Supreme Council for Islamic Revolution in Iraq and Al Dawa -- are now training in independent military camps in a northern province of Iran, the sources said.
"The political faction in Iran that wants to interfere in Iraq is afraid of what lies ahead and is preparing itself for future contingencies," said one well-placed opposition source.
Whether Iran uses the newly established Iraqi factions as proxies inside Iraq may depend on Shiite representation in a transitional government. Shiite Muslims make up the majority in Iran as well as Iraq.
It will also depend on how seriously Washington reacts to Iran's attempts to flex its muscle.
"The United States and Britain will watch this very closely," said a diplomat in Tehran. "There will be a very high level of concern if Iran begins to meddle in its neighbor's affairs."
Iraqi opposition sources said that influential Iranians who oppose the relatively free rein that the Iranian government has granted the Supreme Council for Islamic Revolution in Iraq have provoked a split in the Badr Brigade, the group's military arm.
A former high-ranking member of the Iraqi exile group, Abu Mahdi Mohandes, and a group of fighters from his hometown of Basra, left the Badr Brigade to train independently in a camp in the province of Kermanshah.
"Everyone wants a share in Iraq's liberation," said Sheik Ibrahim Hammoudi, a senior advisor to supreme council leader Ayatollah Mohsen Hakim. Hammoudi confirmed the split but downplayed the military potential of the severed faction.
He said that Mohandes has also gathered supporters from Iraqi refugees living in camps inside Iran, and that he seeks to return to Iraq and control an area of the south.
"The Iranian government doesn't support this," he said, "but some influential people within Iran who have a personal interest in the situation do."
The same Iranian figures have also provoked a rift in Al Dawa, another Shiite opposition group based in Iran that has traditionally retained its distance from the Iranian government.
The splintered camp is reportedly undergoing military training at a camp in Ahvaz and is composed of more militant Iraqis willing to use violence to achieve their political objectives.
The mainstream branch of Al Dawa opposes American leadership of postwar Iraq, but has been explicitly moderate in its opposition.
"We will not take a unilateral political stance," said Abu Bilal al Adib, a senior member of Al Dawa in Tehran, "and we will keep talking with everyone concerned in ways that do not endanger the interests of the Iraqi people."
Iran is also seeking to resurrect the Iraqi Hezbollah, a once-influential party in Iraq that has been inactive for years, said opposition sources. Ala Salmanian, who served in the Iranian Revolutionary Guards, is in charge of the effort.
"Their activities aren't really clear, but they have emerged again politically," said a senior opposition member.
These developments are not yet circulating widely in Tehran, but analysts say they would be in character with Iran's record as well as its desire to undermine the allies' presence in Iraq.
During the U.S. campaign in Afghanistan, American intelligence reported that Iranian agents, exploiting the lawlessness of the immediate period after the fall of the Taliban, threatened and bribed local leaders with the aim of weakening American influence in the country's provinces.
Iran has generally been helpful to the U.S. in its campaign to depose Hussein by downplaying American violations of its territory and airspace in the course of military operations, and by preventing Iraqi opposition members from entering Iran.
Iran, for its part, has been grateful to the allies for targeting the Iraq-based Iranian opposition group Moujahedeen Khalq -- considered a terrorist organization by Washington. Allied forces have attacked several of the group's bases in Iraq, a senior Iranian official said.
Britain has also assisted Iran in recovering the remains of Iranian soldiers found in southern Iraq who had been killed during the Iran-Iraq war of the 1980s.