Iraqi Prime Minister Nouri al-Maliki is in Iran for talks on bilateral relations and security in his country.
The Shi'ite leader is a close ally of Shi'ite Iran, where he once lived in exile.
He met Wednesday with Iranian Vice President Parviz Davoudi, who said Iran is trying to help provide and strengthen security in Iraq.
Mr. Maliki also plans to meet with Iran's President Mahmoud Ahmadinejad and supreme leader Ayatollah Ali Khamenei.
The United States accuses Iran of providing weapons and training to Iraq's Shi'ite militias - a charge Tehran denies.
Also Wednesday, representatives from Iraq, its neighbors, the U.S. and the international community met in Syria for talks on restoring security to Iraq.
Mr. Maliki's visit comes two days after Iraqi, Iranian and U.S. officials met to explore ways to stabilize Iraq.
The United States and Iran have held three rounds of security talks in Baghdad since May. They were the first direct talks between the U.S. and Iran since they severed ties after Iran's 1979 Islamic revolution.
Mr. Maliki traveled to Iran from Turkey, where he agreed with Turkey's Prime Minister Recep Tayyip Erdogan to work together to remove the rebel Kurdistan Workers' Party - or PKK - from northern Iraq.
This is Mr. Maliki's second official visit to Iran. He made his first official visit to Tehran in September of last year.
Some information for this report was provided by AFP, AP and Reuters.