Athens — Ayatollah Muhammad Reza Mahdavi-Kani, a soft-spoken but canny cleric who was elected secretary-general of the militant clergymen's association in early November, is emerging as a powerful force in Iranian politics.
Mahdavi-Kani, who briefly held the post of interim prime minister after the assassination of Ayatollah Javad Bahonar in August, did not sit idle after he was quietly edged off the political stage by Prime Minister Mir Hossein Musavi. Instead, he has been attempting to gain formal control of the fundamentalist Revolutionary Guards corps and the komitehs (revolutionary security centers) all over the country.
If he succeeds it would make him one of the most powerful men in the country. The guards and the komitehs are the force that keep the regime alive.
Mahdavi-Kani already had a firm foothold in the komitehs since the regime came to power in February 1979. From that date until about March 1980 he held the sensitive job of chief of the central komiteh in Tehran.
He apparently did not neglect that power base after he was made interior minister in March 1980 - a brother took over as central komiteh chief. From then , or perhaps earlier, the ground was being prepared to gain control of the Revolutionary Guards, if not by him directly, at least by the group he belonged to: the militant clergymen's association. Today the militant clergymen are seen to be in control of a surprisingly large number of the komitehs around the country, and are interfering directly in the affairs of the guards.
The guards have been in turmoil recently, sources in Tehran say, and have been demanding that mullahs should not interfere in their affairs. But Mahdavi-Kani paid a visit to Ayatollah Khomeini a few days ago and received from him the authority for members of the militant clergymen's association to be appointed to ''supervise'' the affairs of the Revolutionary Guards and the komitehs in the capital and the provinces, but not to ''interfere directly'' in their affairs.
Since there is a very thin line between ''supervising'' the affairs of the guards and ''interfering directly'' in them, this would in effect put the militant clergymen in control of both the guards and the komitehs.
Ayatollah Khomeini has repeatedly stressed in recent speeches that the authority of the mullahs must be maintained. This may have been one motivation for him to have given Mahdavi-Kani the authority to ''supervise'' the guards and the komitehs through the clergymen's association.
Mahdavi-Kani's next move will probably be to try to legalize all this through a bill in the Majlis (parliament). The bill will probably cause a lot of confusion in the already divided house, where a struggle for control has been going on between the hard-liners in the Islamic Republican Party and the group within the IRP calling itself the ''Mujahideen of the Islamic Revolution.'' This group wants to diminish the role of the mullahs in the Iranian administration.
A more intriguing report, however, is that Mahdavi-Kani has recently also forged an alliance with former Prime Minister Mehdi Bazargan. The form of the alliance is not quite certain yet, but the two have been meeting almost every day recently and are seen to be attempting to set up a new Iranian political party.
Mr. Bazargan has recently expressed support for the Islamic-leftist Mujahideen-e Khalq guerrilla organization, which has been involved in a 5 1/2 month struggle against Khomeini. As a former member of the Mujahideen-e Khalq himself, Mahdavi-Kani could not be entirely without sympathy for them, and indeed one of the criticisms against him during his term as interim prime minister was that he had not acted firmly enough against the guerrillas.
Observers also recall that the militant clergymen's association was instrumental in the presidential victory of Bani-Sadr in the January 1980 election.
Mahdavi-Kani chose to sit on the fence during the height of the power struggle between Bani-Sadr and the Islamic Republican Party. He is not on record as having leveled any criticism against Bani-Sadr either during the power struggle or after Bani-Sadr was ousted and fled to Paris.
Against this backdrop, some observers in Iran are beginning to speculate about what kind of lineup could emerge against the ruling Islamic Republican Party if Mahdavi-Kani does gain control over the Revolutionary Guards and the komitehs.
The strongest opposition to Mahdavi-Kani is coming from the IRP. And the guards themselves are so divided into groups that it is by no means certain they are going to easily allow themselves to come under the control of the militant clergymen. Said one resident in Tehran: ''Each group is pulling in a different direction and it is difficult to tell where it is all going to end.''