Shahla Ghassempour, a middle-aged Tehran homemaker, emerged from a corner store with a heavy sack. The heft in her bag, however, was not the day's groceries, but an assortment of the latest pro-democracy and reformist political books that have swept onto Iran's bestseller list.

Ghassempour, like thousands of Iranians, is setting aside traditional romance novels and plucking up hot-selling titles that promote political change, champion the country's pro-democracy student movements and explore a series of killings of writers and dissidents that took place in 1998. "I will go home, put on a pot of tea and begin reading every one of them," Ghassempour said, pointing to the six books in her sack.

The books, which also include attacks on Iran's powerful conservative establishment, have set off a flurry of debate in offices, mosques, newsrooms and dinner tables.

Unlike most of its neighbors, Iran is experiencing a serious national debate on the merits of democracy. The latest wave of books, analysts and publishers say, strengthen democracy forces and obliterate previously observed "thou shalt nots" in Iran's increasingly daring media. The most discussed bestseller is a reformist tract by an outspoken pro-democracy cleric, Abdollah Nouri, who was sentenced by a conservative clerical court recently to five years in prison for political and religious dissent.

Nouri's book, "Hemlock of Reform," has sold more than 60,000 copies in less than a month. It is a print version of his explosive trial statement, in which he attacked several pillars of Iran's powerful clerical leadership, including the normally untouchable supreme leader, Ayatollah Ali Khamenei, who is seen as close to the conservatives.

Since the landslide election of reformist President Mohammed Khatemi more than two years ago, Iran's influential conservatives have been engaged in a political battle with an increasingly vocal and active reformist movement led by journalists, politicians, clerics and students. Conservatives believe they are defending Iran's revolutionary and Islamic values against reformers' calls for democratic innovations.

In the book, Nouri attacks the court that prosecuted him and questions the authority of Khamenei, an all but taboo subject here. "The supreme leader should not be considered above the law of the land," Nouri wrote.

Refusing to be silenced, Nouri has pressed his defense from his prison cell. He has written letters to newspapers criticizing such sacred cows as Iran's anti-U.S. policy and defending dissidents' rights--thus fueling sales of his book and angering reactionary clerics. Street opinion in Iran overwhelmingly supports improved ties with Washington, although Khamenei threw cold water on those hopes last month in a sermon laced with anti-U.S. sentiment and implicit attacks on Nouri.

"Nouri is seeking to undermine the legitimacy of the supreme leader," a leading hard-line cleric said in an interview at a mosque in central Tehran. "This is an offense to the constitution." As he spoke, a group of worshipers at the mosque sat cross-legged on exquisite Persian rugs discussing the issue. "Nouri is going too far," said Hossein Marashi, an accountant. "He should be careful."

"I disagree," said Mohsen Malekzadeh, a 33-year-old engineer who recently bought Nouri's book. "He should be given the right to speak just like everyone else."

Another bestseller, by Iran's leading investigative journalist, delves into the 1998 killings of five writers and dissidents, allegedly by a group of government intelligence agents.

Meanwhile, a seemingly dry chronicle of the statements of various political groups during last summer's tumultuous student protests also also become a bestseller. On the surface, it seems an unlikely success, but publishers and book dealers attribute the book's sales to its rare photos of protesting students. In one photograph, a longhaired, black-bearded student with a resemblance to Che Guevara holds up the bloodstained shirt of a fellow student.

"People take one look at the book's cover photos and decide to buy it right away," said Ali Khosrow, a Tehran bookstore owner.