TEHRAN, Iran — Squashing a cherished goal of President Mohammad Khatami and his reformist allies, Iran's supreme religious leader Sunday sided conclusively with the country's conservatives and ordered the Parliament to scrap a bill aimed at restoring a free and lively press.

The intervention by Ayatollah Ali Khamenei, the country's top Muslim cleric, stunned reformers, dashing their hopes of using their newly won strength in Parliament to push through reforms, and set off scuffles and loud arguments in the chambers. Sixty liberal members walked out in protest.

The proposed law to liberalize the press was the centerpiece of Khatami's reform program for the new Parliament and followed many months where liberal newspapers had been shut down and their editors and writers jailed. The 22nd newspaper was closed Sunday.

The parliamentary showdown was a decisive moment in the struggle between liberal and conservative forces that has simmered in the three years since the reform-minded president was swept to power on an electoral landslide generated largely by a youthful electorate that has come of age since the Islamic revolution of 1979.

That battle took on new momentum with the victory of reform politicians in parliamentary elections six months ago. But since then, Khatami's supporters have suffered successive blows as conservative courts have denied them a voice to reach the public in the press.

During the past two months, the pro-Khatami forces had said that their chief aim was to pass a new press law that would permit a resumption of the lively public debate over the direction of the country.

In quashing the reformers' paramount goal Sunday and refusing even to permit a debate on the bill, Khamenei took the exceptional move of circumventing the normal institutional checks on legislation.

The Iranian Parliament, while directly elected, is relatively weak. Mehdi Karrubi, the Parliament speaker, said Khamenei, who has held his post since 1988, had the constitutional power to order the lawmakers to stop consideration of a bill. The system, he said, is based on submission to the "absolute rule of the supreme leader."

But other leaders disagreed and said the measure should have been put to a vote.