To no one's surprise, Iranian clergymen and supporters of Ayatollah Ruhollah Khomenini's fundamentalist Islamic Republican Party have won a commanding majority in an assembly that will debate and amend Iran's future constitution.

But complaints about the voting procedures and results of Friday's national elections for the assembly - especially by regional minorities - are challenging the body's mandate and undermining what little hope remains of installing a freely elected government in increasingly ungovernable Iran.

So far, winners have been announced for 63 of the constituent assembly's seats, with only the results for the capital, Tehran, still to come.

As the election results continued to trickle in, an NBC television crew which arrived Saturday to cover the latest Iranian developments said tonight that it has been ordered by the Ministry of National Guidance to leave the country within 48 hours.

The delay leaves open the possibility that some of them may be disqualified after investigation of complaints about illegal election practices, or because they do not meet criteria laid down by Khomeini.

Despite elaborate voting procedures that observers said helped to keep the election one of the freest in decades, evidence has been collected that campaign posters, particularly those of the Islamic Republican Party, were displayed inside polling stations, that scribes often wrote the names of their favorite candidates on the voting slips of illiterates and that children under the age of 16 were being used to swell the balloting.

There were also charges that results were rigged more directly by disposing of ballots and inflating the counts of favored candidates.

The authorities apparently do no intend to let proceedings be delayed by the investigations, however. Sabbaghian has announced that the assembly's inaugural meeting will be held Saturday.

The crew quoted Ali Behzadnia, a medical doctor who lived for a dozen years in the United States before returning to Iran to become the ministry's director for foreign press, as saying that the ruling Revolutionary Council had decided not to let any new correspondents into the country for the next two months.

Meanwhile, Islamic firing squads executed six more persons today, bringing to at least 336 the number of those tried and shot since the February revolution.

A precise party breakdown for the election results was not immediately available because of the absence of official lists of candidates, the small number of nationally known names among those announced and a significant number of candidates who shared the nominations of two or more parties.

Adding to the uncertainty was a statement by Interior Minister Hashem Sabbaghian that the 63 winners announced had received the majority of votes in their constituencies but had not been officially recognized yet as representatives to the assembly.

Political party sources said they doubted that the various alleged illegal practices greatly affected the outcome of the election, but in some areas they have stirred bitter controversy.

Kurdish leaders have responded angrily to the election of two Shiite Moslem clergymen in the western province of Kurdistan where the majority of the population are Sunni Moslems.

As news of the clergymen's election on an extremely low number of votes was announced, Kurdish leader Sheik Ezzedine Hosseini warned "these people are not the real representatives of Kurdistan. We do not accept these people."

There have been angry complaints from the Islamic Republican Party's chief rival, the Moslem People's Republican Party, over the results in the northwestern provinces of Azerbaijan, where voters turned out in force for the Moslem People's Republican Party although it had announced it was boycotting the election.