Afghan President Hamid Karzai arrived in Iran for talks Sunday amid disagreement with the United States over a security accord that would allow some NATO forces to stay in Afghanistan.
Karzai will meet President Hassan Rouhani -- for the second time in four months in Tehran -- and Foreign Minister Mohammad Javad Zarif, the official IRNA news agency reported.
The proposed deal allowing NATO troops to operate in Afghanistan after 2014 will be discussed during the talks, according to the ISNA news agency.
Tehran strongly backs Karzai's stance in refusing to sign the deal.
His trip comes a day after an awkward visit to Kabul by US Defence Secretary Chuck Hagel amid growing disagreement with the Afghan president over the long-delayed security accord.
Hagel did not meet Karzai, which would have been customary for a Pentagon chief, saying that Kabul was already aware of the US position.
Washington and its allies have appealed to Karzai to sign the Bilateral Security Agreement (BSA).
This lays out the rules for US and other NATO troops to operate in the country after 2014 on a mission focused on training, and countering Al-Qaeda-linked extremists.
Iran's position on the BSA is that it would not serve the interests of its eastern neighbour.
"Iran does not see the signing and ratifying of this security pact to be beneficial for the long-term interests of the people and government of Afghanistan," foreign ministry spokeswoman Marzieh Afkham said Tuesday.
Karzai initially endorsed the BSA, but has since refused to sign it and issued fresh demands.
The security agreement sets the legal conditions to permit roughly 12,000 NATO troops -- mostly American -- to remain in Afghanistan.