TEHRAN, Iran -- Greeted by throngs of supporters wearing white as a symbol of peaceful change, Nobel Peace Prize winner Shirin Ebadi returned to her homeland Tuesday as the new guiding force of the reform movement.

"Many thanks to all of you," she said as well-wishers -- including dozens of reformist parliament members -- surged into the VIP lounge at Tehran's international airport. Outside, more than 5,000 people gathered in the biggest pro-reform rally since violent street demonstrations in June.

The 56-year-old lawyer and rights campaigner, who set foot in Iran for the first time since Friday's Nobel decision, is now considered by many as the possible savior of the embattled effort to weaken the ruling cleric's monopoly on power. But hard-liners have denounced her as a foe out to dismantle the Islamic system through Western-backed rights campaigns.

Earlier -- in an attempt to appease both sides -- pro-reform President Mohammad Khatami lauded the rights activist's success but called the award a "political" tool.

Fearing possible clashes, security forces took positions around the airport. Huge traffic jams forced many people to abandon their cars and continue on foot as the crowd swelled.

Many women wore white head scarves in support of Ebadi's calls for peaceful reforms and greater attention to human rights. Men wore white shirts and carried white flowers.

"Messenger of peace," read some placards. Another showed a map of Iran behind prison bars with the slogan: "Torture has no effect anymore."

Ebadi was presented with a wreath of flowers.

"This prize does not belong to me. It belongs to all the Iranian people. It belongs to all those who have been trying to bring human rights and democracy," she told supporters. "My heart is with all of you."

Ebadi, wearing a red headscarf and black coat, repeated: "Allahu Akbar," or God is great.

The double-edged comments by Khatami -- his first public reaction since the Nobel decision -- apparently sought to appease both sides at odds over Ebadi, who was in Paris when the prize was announced.

"This award has been given to her totally on the basis of political considerations," Khatami told reporters. He called the Peace Prize "not very important" compared with other Nobel awards, such as literature.

But he also praised Ebani's sudden fame.

"Nobody will be unhappy to see the success of a fellow Iranian," Khatami said. "I am also happy an Iranian has achieved success. I hope this achievement will be used for the interests of the nation and the world."

There were fears the country could become further polarized if Ebadi maintains her high-profile work, which includes campaigns for women's rights, protection for children and refugees and greater political freedoms.

Ebadi was Iran's first female judge, but lost her post in the 1979 Islamic Revolution after clerics ruled women could not longer preside in court.

As a lawyer, she represented families of writers and intellectuals killed in 1999, and worked to expose conspirators behind an attack by pro-clergy assailants on students at Tehran University in 1999.

Ebadi and another lawyer were arrested in July 2000 for alleged links to a videotape that purportedly revealed ties between government officials and hard-line vigilantes. They were released from jail after three weeks and later given suspended prison sentences.

Hard-line figures have clearly interpreted Ebadi's new stature as a threat, but it was unclear how they would respond.

"With little doubt, we can say that the goal of this prize is to embarrass Muslims and, especially, the Iranian people," said a commentary in the Kayhan newspaper, a leading conservative voice.