Iran's powerful Guardian Council is due to give its verdict on the result of the disputed presidential election, two weeks after the poll was held, BBC reported.
Opposition leader Mir Hossein Mousavi has refused to support the electoral authority's plan for a partial recount.
Mr Mousavi wants a re-run of the vote, but said on Saturday that he would accept a review by an independent body.
However the Guardian Council has already backed President Ahmadinejad's re-election as a fair result.
On Friday it said the presidential election was the "healthiest" held since the Iranian revolution in 1979.
Some 17 people are thought to have died in street protests in the past two weeks, and Tehran has imposed severe restrictions on journalists, blogs and other media.