(CNN) -- Authorities in Tehran, Iran, have given the go-ahead to execute a woman who initially was sentenced to death by stoning, according to an activist working on her behalf.
However, what method will be used to execute Sakineh Mohammadi Ashtiani is unclear, said Mina Ahadi, spokeswoman for the International Committee Against Stoning. The execution could happen as soon as Wednesday, she said, citing information received from a source in Tabriz, Iran, who is close to Ashtiani's family.
Ashtiani initially was sentenced to death by stoning for adultery. The Iranian government later said she was also convicted of murdering her husband, but her lawyer and family dispute that.
A letter from Tehran was delivered to the prison in Tabriz where Ashtiani is being held three days ago, Ahadi said, giving the go-ahead for Ashtiani's execution.
Ashtiani, 43 and a mother of two, drew international attention when she was sentenced to death by stoning. She concedes that she was convicted of adultery, as initially reported, but says she was acquitted of murder. "The man who actually killed my husband was identified and imprisoned, but he is not sentenced to death," she said in August.
The Iranian government's claims that she was convicted of murder are a lie, she told the Guardian newspaper through an intermediary. "They are embarrassed by the international attention on my case, and they are desperately trying to distract attention and confuse the media so that they can kill me in secret."
Ashtiani's son and her attorney are still in jail after being arrested last month, Ahadi said. Also still detained are two German journalists.
"The International Committees against Stoning and Execution call on international bodies and the people of the world to come out in full force against the state-sponsored murder of Sakineh Mohammadi Ashtiani," as well as the release of the others, Ahadi said in a statement.
Before his arrest, Ashtiani's son, Sajjad Ghaderzadeh, said court officials stole documents and files pertaining to the murder of his father in order to "promote his mother as a murderer." And Ahadi's committee said the murder charges are "fabricated" by the Iranian regime.
In August, Ashtiani appeared on state TV confessing that she knew about a plot to kill her husband but felt she had been misled. Amnesty International condemned the interview.
Ghaderzadeh and attorney Hootan Kian will not be issued an attorney, because the government claims they do not need one, according to Ahadi.
Ashtiani's other former lawyer, Mohammad Mostafaei, is being protected by European diplomats after he fled to Turkey from Iran.
Mostafaei claims that Iranian authorities tried to arrest him without cause.