Tehran, Iran ? Mahmoud Ahmadinejad’s main reformist challenger said Sunday that the Iranian president has made false accusations against his supporters to try to sabotage his campaign with just days to go before Friday’s presidential election.

Former Prime Minister Mir Hossein Mousavi wrote a letter to Iran’s supreme leader, Ayatollah Ali Khamenei, accusing Ahma-dinejad and his supporters of taking unethical steps against his campaign.

“Is the presidency worth lying to people?” Mousavi said later Sunday during a live TV debate with the other reformist challenger, Mahdi Karroubi.

Mousavi said he joined the race to protest that Ahmadinejad “has dragged the country to a point that it is full of lies.”

In an unusual twist for elections in Iran, the presidential campaign has descended into bitter personal attacks between candidates. Khamenei, who has final say on all state matters in Iran, has urged the contenders and their supporters to exercise restraint.

That call has gone unheeded, and a handful of political figures who are not even running in the campaign — as well as some of their relatives — are threatening to sue Ahmadinejad for publicly accusing them of corruption.

In the latest round, Mousavi’s letter to the supreme leader said, “There is a possibility of fabrication of evidence against my supporters,” according to several Iranian news reports published Sunday.

The reports gave no details of what Mousavi was alleging Ahmadinejad and his campaign have done specifically to target his supporters.

Officials with Mousavi’s campaign confirmed Sunday that the letter was sent but refused to provide a copy to reporters or elaborate on its contents.

Ahmadinejad has previously accused Mousavi of having links with people involved in corruption.

Mousavi said during Sunday’s debate that Ahmadinejad has also made false accusations about the rate of inflation in the country, saying it was 15 percent when Iran’s central bank reported 25 percent. He also claimed Ahmadinejad provided inaccurate or misleading statistics about the production of steel in the country and the gap between rich and poor.

When the moderator tried to stop Mousavi from making accusations about Ahma-dinejad in his absence, the candidate said, “Ahmadinejad lies here on television, but you do not protest him.”

Mousavi, who was prime minister during the country’s years of war with Iraq in the 1980s, is among Iran’s reformist camp, which seeks better ties with the West and an easing of social and political restrictions at home.

The hard-line Ahmadinejad’s four years in office have been characterized by antagonism with the United States and its European allies over Iran’s forward strides in its nuclear program, which they say is aimed at producing weapons. Iran denies the charge and says it only seeks peaceful nuclear energy.