An Iranian activist said a woman sentenced to death by stoning for adultery could be executed as early as Wednesday, citing sources close to the court.

"We received the information three days ago," exiled human rights activist Mina Ahadi told AFP by telephone Tuesday, citing a letter sent from a court to the northwestern city of Tabriz where Sakineh Mohammadi-Ashtiani is in custody.

"If the decision is taken, she could be executed on Wednesday. We are very afraid."

Ahadi said her organisation, the International Committee Against Stoning, planned a two-day march from Paris to Brussels on behalf of Mohammadi-Ashtiani beginning Tuesday.

"We want to make the media aware and convince governments to step up the diplomatic pressure (on Iran)," she said.

Mohammadi-Ashtiani was sentenced to death by two different courts in Tabriz in separate trials in 2006.

The first death sentence, by hanging, for her involvement in the murder of her husband, was commuted to a 10-year jail term by an appeals court in 2007.

But the second, by stoning, was on a charge of adultery levelled over several relationships, notably with the man convicted of her husband's murder, and was upheld by another appeals court the same year.

Since July, Iran has repeatedly said that the stoning sentence has been stayed pending a final decision, amid international outcry over the case.

Mohammadi-Ashtiani's son Sajjad Ghaderzadeh and lawyer were arrested in Iran last month, as were two German nationals, reportedly while interviewing the son. The Germans were granted consular access in late October.

The International Committee Against Stoning has called for the inmates' immediate and unconditional release.

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