Iran has invited the Iraqi and Syrian presidents to Tehran for a weekend summit with Mahmoud Ahmadinejad to hash out ways to cooperate in curbing the runaway violence that has taken Iraq to the verge of civil war and threatens to spread through the region, four key lawmakers told The Associated Press on Monday.

Iraqi President Jalal Talabani has accepted the invitation and will fly to the Iranian capital Saturday, a close parliamentary associate said.

The Iranian diplomatic gambit appeared designed to upstage expected moves from Washington to include Syria and Iran in a wider regional effort to clamp off violence in Iraq, where more civilians have been killed in the first 20 days of November than in any other month since the AP began tallying the figures in April 2005.

The Iranian move was also a display of its increasingly muscular role in the Middle East, where it already has established deep influence over Syria and Lebanon.

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"All three countries intend to hold a three-way summit among Iraq, Iran and Syria to discuss the security situation and the repercussions for stability of the region," said Ali al-Adeeb, a lawmaker of Prime Minister Nouri al-Maliki's Dawa Party and a close aide to the prime minister.

Both Iran and Syria are seen as key players in Iraq. Syria is widely believed to have done little to stop foreign fighters and al-Qaida in Iraq recruits from crossing its border to join Sunni insurgents in Iraq. It also has provided refuge for many top members of Saddam Hussein's former leadership and political corps, which is thought to have organized arms and funding for the insurgents. The Sunni insurgency, since it sprang to life in late summer 2003, has been responsible for most of the U.S. deaths in Iraq.

Iran is deeply involved in training, funding and arming the two major Shiite militias in Iraq, where Tehran has deep historic ties to the current Shiite political leadership. Many Iraqi Shiites spent years in Iranian exile during Saddam's decades in power in Baghdad. One militia, the Badr Brigade, was trained in Iran by the Revolutionary Guard.