Iran moved a step closer to institutionalizing a government of Moslem theologians today with the publication of a constitutional clause giving supreme power to a religious leader.

Iran's Assembly of Experts, charged with revising the country's new constitution, introduced the clause Wednesday, paving the way for Ayatollah Ruhollah Khomeini to be formally named leader of the Islamic Republic.

The clause dispenses with any need for elections to choose the country's effective head of state and casts considerable doubt over the role envisaged for the future president, who originally was to have become Iran's top official according to the draft constitution.

The new article assigns overall authority to a religious leader in the absence of the Twelfth Imam -- a reference to the Shiite Moslem leader who disappeared more than a thousand years ago and who, according to Shiite teaching, is destined to reappear.

Passed by 53 votes to eight, with four abstentions, the new article decrees that "in the absence of the Twelfth Imam, guardianship of affairs and leadership of the nation is in the hands of the honest, efficient, aware theologian, whose leadership has been accepted and recognized by the people."

The clause adds: "In case there is no one with these qualifications, a council of theologians will take over. Formation of the council and appointment of its members will be defined by law."

If, as seems a foregone conclusion, the draft constitution is approved in a referendum due to be held shortly, Ayatollah Khomeini would emerge as head of state with no need for elections.

The original draft of the constitution said the head of state would be a president elected by direct popular ballot.

Coinciding with the introduction of the new article were reports of proposals for the formation of a "leadership council" apparently to help carry out the duties of the head of state.

Election of the five-man council would not be by Parliament but by a different "assembly of experts."

The leader, according to this proposal, would have the power to appoint or dismiss the president, approve candidates for the office and call a referendum.

One of the few secular members of the assembly, Ramatollah Moghaddam Maragheh, criticized the new article on the grounds that it went against article three of the draft constitution.

In the original draft considered by the assembly, Article 3 said "The will of the people constitutes the basis of government, and the affairs of the country must be settled by councils elected by the people."

Maragheh warned, "If you are going to give powers of government to a specific group by using the power of Islam, this will not be acceptable to society."