Tehran, Iran (CNN) -- Despite international pressure, Iran said Tuesday that it rejects Brazil's offer of asylum for an Iranian woman sentenced to death by stoning.

Brazilian President Luiz Inacio Lula da Silva proposed Saturday to give sanctuary to Sakineh Mohammadi Ashtiani, whose case has garnered global attention.

Iranian Foreign Ministry spokesman Ramin Mehmanparast said Lula lacked sufficient information about the case, the state news agency Agencia Brasil said.

Ashtiani was convicted of adultery in 2006 and was originally sentenced to death by stoning. Iranian authorities say the sentence has been put on hold, but there have been no reports as to whether a new sentence has been imposed.

Meanwhile, a human rights activist who has taken up Ashtiani's case penned a letter to Lula, saying that his offer was an "important step" in saving Ashtiani from undue punishment.

Mina Ahadi of the International Committee against Stoning said the campaign to save Ashtiani's life will continue. She said she hopes Brazil and other governments will keep up pressure on the Islamic regime in Tehran, which she said rules through fear and punishment and should not be recognized by the international community.

"Allow me, as a representative of the oppressed people in Iran, to say that I not only want to save Sakineh and abolish stoning, but that I also ask all heads of state not to recognise the Islamic regime as the representative of the Iranian people but to see it as the murderer of people in Iran," Ahadi wrote in her letter to Lula.

Brazil's relations with Iran have improved in recent years and it recently participated in talks with Tehran aimed at restarting negotiations about Iran's nuclear program. In May, Brazil helped broker a deal with Iran that would provide the government with enriched uranium for medical research.

Ashtiani, a 43-year-old mother of two, is reportedly still being held in Tabriz prison. Iran's judiciary could reinstate her sentence of death by stoning, execute her by other means, or possibly even grant her a reprieve, according to human rights groups.

Ashtiani's attorney, Mohammad Mostafaei, has gone into hiding since last weekend after being interrogated by Iranian authorities, human rights groups say. Advocates and Mostafaei say his wife and brother-in-law are being held by Iranian authorities.