"This is a campaign to secure the repeal of the stoning law so that there will be no further such verdicts carried out," women's rights lawyer Shadi Sadr told the news agency.
She said research conducted by fellow activists had shown that the sentence had been handed down by a court in the north-eastern pilgrimage city of Mashhad as recently as April against a man and a woman convicted of adultery.
"In our investigations, we found out about nine women and two men in different Iranian jails who had been sentenced to stoning," she said.
"The lawyers of seven of these convicted women have expressed their concern in writing to the head of the judiciary (Ayatollah Mahmoud Hashemi Shahrudi) calling for a change in the law."
Executions by stoning have been suspended by the judiciary since late 2002, when the European Union opened now suspended trade talks with Iran and made human rights issues a key condition to negotiations.
The judiciary has acknowledged that stoning sentences may have been issued by lower courts, but asserts that they are invariably quashed on appeal or by the supreme court -- which has to approve all executions.
Human rights activists and diplomats have said that while Iran appears to have respected a moratorium on stoning, there have been cases of minors being executed.
The law provides that before being stoned, men should be buried up to their hips and women up to their chests. They are to be spared if they manage to work themselves free.
The law also stipulates that the stones should be the size of a fist but not so big that they kill the convict too quickly.
Capital offences in the Islamic republic include murder, rape, armed robbery, apostasy, blasphemy, serious drug trafficking, repeated sodomy, adultery or prostitution, treason and espionage.

Copyright AFP (Agence France-Presse), 2006