The Iranian government has no legal basis for detaining a female Iranian-American student doing research in Iran, her lawyer said Saturday.

Mohammad Ali Dadkhah said no formal charges have been brought against Esha Momeni but officials at the Revolutionary Court privately told her parents her detention was related to her involvement in the "Change for Equality" campaign launched by Iranian women activists in September 2006.

"There is no legal basis for Momeni's detention. She has to be released now ... an opponent or a dissident can't be jailed as long as he or she doesn't take up arms against the ruling establishment," Dadkhah told The Associated Press.

Court officials and prosecutors could not be reached for comment Saturday.

The 28-year-old Los Angeles-born graduate student at California State University was pulled over by police Oct. 15 for an alleged driving violation but was later taken to Evin prison, north of the capital Tehran, where she remains in detention.

Security agents also searched Momeni's home and seized her computer and footage of interviews she had conducted as part of her research with women activists.

The "Change for Equality" campaign seeks to collect a million signatures in support of changing laws that deny women in Iran equal rights in matters such as divorce and court testimonies.

Momeni returned to Iran two months ago to see her family and do research for her master's degree thesis about women movements in Iran.

Court officials have not allowed Dadkhah to meet his client, which he said was common — though illegal — when defendants are in "temporary detention," which cannot last for more than two months.

Dadkhah said the 28-year old Momeni was being held in the infamous Section 209 of Evin, controlled by Iran's Intelligence Ministry.

Momeni's friends and women activists have launched a campaign to free her, asking visitors to sign an online petition calling for her release.

Melissa Wall, one of Momeni's teachers, said on her Web site that professors in California State University at a news conference Friday talked about how Momeni wanted the two worlds of America and Iran to better understand each other.

Four Iranian-Americans scholars were jailed for several months and subsequently released last year over charges of endangering national security. The four came under suspicion by Iranian authorities of being part of a plot to foment a "velvet conspiracy" against the Islamic government.