Sources familiar with the investigation into the assassination of Rafik Hariri in 2005 told Newsmax that the United Nations Special Tribunal for Lebanon will accuse Iranian Supreme Leader Ayatollah Khamenei of giving the order to murder the former Lebanese prime minister, according to the Lebanese website Naharnet.

The sources told Newsmax, an American news website, that the tribunal will lay out evidence showing that the murder was committed by Iran's Quds force and Hezbollah

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The order to murder Hariri was transmitted to Imad Mughniyeh, Hezbollah's top commander at the time, by Quds force chief Qassem Suleymani, sources familiar with the investigation told Newsmax.

The sources said Mughniyeh and his brother-in-law, Mustapha Badr al-Dine, put together the hit team that carried out the attack. "The Iranians considered Hariri to be an agent of Saudi Arabia, and felt that killing him would pave the way for a Hezbollah takeover of Lebanon," one of the sources said.

According to the sources, Syrian President Bashar al-Assad, and his brother-in-law, Assef Shawkat, the head of Syrian intelligence, also played key roles in the assassination plot.

A few days ago Hezbollah toppled the government of Saad Hariri, son of the assassinated former prime minister. Saad Hariri returned to Lebanon Friday after visiting the US and France.

In his first public reaction to the collapse of the government on Wednesday, Hariri said he would support President Michel Suleiman's efforts to form a new government but did not specify if he would be a candidate to lead it.

"There is no alternative for all of us to dialogue, and no side in Lebanon will be able to eliminate the other," Hariri said after talks with Suleiman at the president's office.

Hariri described the resignation of 11 ministers, which brought his government down, as an "unprecedented" move in Lebanese politics.

His government was toppled over a rift with Hezbollah about expected indictments by the UN-backed tribunal investigating the 2005 assassination.

Hezbollah, which is supported by Iran and Syria, expects the tribunal to accuse its members over the 2005 killing. It has denied involvement and called for Lebanon to withdraw all support for the tribunal. The Shiite group has hinted that it would seize control of Lebanon if its members are charged.

Reuters contributed to the report