Recep Tayyip Erdogan vowed on Sunday to ratchet up bilateral trade in talks with Mahmoud Ahmadinejad, the Iranian president and Parviz Davoudi, the vice-president.
During the one-day visit to Tehran, Erdogan also discussed Iraq during talks with supreme leader Ayatollah Ali Khamenei.
He said that Iran and Turkey could soon be looking to increase trade to $10bn per year, a huge rise on the figure of $1.2bn from 2002 and the current $6bn.
"The main aim of this trip is to study the rapid international development, especially the sensitive situation in Iraq, Palestine, Lebanon, and the responsibility that both nations feel in finding a solution," state television quoted Erdogan as saying.
Güncelleme Tarihi: 20 Eylül 2018, 18:16
"Iranian and Turkish officials want to extend and boost ties," said Ahmadinejad. "Tehran and Ankara can expand bilateral trade and even jointly invest in other parts of the world together."
Khamenei told Erdogan that US forces must make a quick exit from Iraq, predicting that the longer they stayed in the violence-torn country the deeper they would sink in the "Iraqi quagmire".
"If the current US President [George Bush] does not pull out troops from Iraq the next US president will be forced to do so," he said.
"Just as in the Vietnam war, the US troops will be pulled out in disgrace," he said.
Iran and Turkey share a border, a common interest in stemming the activities of Kurdish fighters operating inside their territories, and concerns about the security situation in Iraq.
But Tehran's relations with Ankara have not always been smooth. Turkey is the closest Muslim ally of the Islamic republic's arch-enemy Israel, and also has a key strategic relationship with Iran's other enemy - the United States.