Head of Iraq's Sadrist movement, cleric Moqtada al-Sadr had received "direct threats from Iran" to reach an agreement with the pro-Tehran Coordination Framework over the formation of a new government, revealed Iraqi and Lebanese sources.
These threats were made days before his bloc resigned from parliament last week.
Iran has denied the claims.
Iraq was plunged deeper in political turmoil after Sadr's bloc quit after failing for months in reaching an agreement with the Framework over the formation of a government.
A Lebanese source close to Hezbollah's management of Iraqi affairs told Asharq Al-Awsat that Sadr "opted to resign rather than yield to pressure from Iran."
He said Iran had used maximum pressure with Sadr and that its efforts are largely tied to its nuclear deal negotiations with the West.
The source did not rule out the possibility that Tehran was also concerned that the prolongation of the crisis in Iraq would impede its plans there.
A high-ranking Kurdish source revealed that Sadr had informed his coalition partner, Masoud Barzani, of the Iranian threats.
The Framework has meanwhile, kicked off efforts to form a government, starting with the naming of a prime minister.
The process will not be easy given the sharp divisions within the group.
Moreover, the Framework is expected to approach Kurdish parties, including Barzani's Kurdish Democratic Party, and his position is unlikely to veer off from Sadr's meaning he would rather withdraw from the process or reach a settlement over main Kurdish demands related to the system of rule.
The Framework itself is divided over the formation of the government.
On the one hand, the State of Law coalition wants to name a prime minister without Sadr's approval, while other parties, such as Ammar al-Hakim and Hadi and Ameri, want to include the cleric in the process in order to gain some of his favor to avert future opposition to the government from his large popular base.