Zahra Bahrami, who was detained after taking part in anti-government protests in 2009 and later charged with drug smuggling, was hanged Saturday, RIA Novosti reported.
Bahrami's daughter said the drug charges were fabricated after her mother was arrested for taking part in the demonstrations, which occurred while she was in Iran visiting relatives.
Bahrami, 45, was charged with smuggling 450 grams of cocaine into Iran from the Netherlands.
Bahrami's lawyer said she is shocked by her client's execution and that she knew nothing about it until a news agency contacted her.
"I am shocked. I was absolutely not informed about this," said attorney Jinoos Sharif Razi. "They should have informed her lawyer of the execution, but I had no idea. I don't know what to say. Just that I am shocked."
Fars New Agency, a semi-official news agency with ties to the Iranian government, called Bahrami a "drug trafficker" and said "she was a member of an international band of drug traffickers who through help from her Dutch contact, smuggled cocaine from the Netherlands to Iran."
Dutch Foreign Minister Uri Rosenthal expressed "extreme concern" over the charges against Bahrami earlier this month.
In an interview with the International Campaign for Human Rights in Iran, Bahrami's daughter said her mother told her she was forced to confess to the drug charges after her arrest.