Three Iraqi opposition leaders met in the Iranian capital Monday to discuss the toppling of Saddam Hussein, official media reported, part an effort to narrow differences ahead of this week's London conference of all Iraqi opposition groups.

Massoud Barzani, heads the Kurdistan Democratic Party, met separately with Mohammed Baqir al-Hakim and Ahmad Chalabi to exchange views on Iraq's future once Saddam is ousted, the Islamic Republic News Agency reported.

Barzani's party controls large parts of northwestern Iraq; al-Hakim leads the Tehran-based Supreme Council of the Islamic Revolution in Iraq, which enjoys support from Shiite Muslims -- who are the majority of the Iraqi population; and Ahmad Chalabi is a pro-Western figure heading the Iraqi National Congress.

The Iranian news agency said the three men confirmed their joint objectives of toppling Saddam and exchanged views on the election of a leader to be accepted by all Iraqi groups after Saddam's fall.

IRNA said Barzani's rival, Jalal Talebani of the Patriotic Union of Kurdistan, may travel to Iran in the coming days.

The United States has been pressing the fragmented opposition to Saddam to overcome its differences for the conference in London, which begins Friday and goes on for three-days.

On Sunday, al-Hakim told The Associated Press that he had documents proving Saddam was hiding weapons of mass destruction. He added that he was prepared to give the information to the United Nations if it guarantees the safety of his informants inside Iraq.

The United States -- which is threatening war to disarm Iraq -- rejects Baghdad's denials it has weapons of mass destruction, saying it holds evidence proving Baghdad's possession of such arms.