Iraqi Prime Minister Nouri al-Maliki is in Iran for talks expected to focus 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. He also plans to meet with Iranian President Mahmoud Ahmadinejad and the country's 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.
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, reports Voice of America.
It was al-Maliki's second visit to Tehran in less than a year, coming days after U.S. and Iranian experts held talks in Baghdad on improving Iraq 's security.
Al-Maliki and the Shiite and Kurdish parties that dominate his government are closely linked to predominantly Shiite Iran, and he has struggled to balance those ties with the United States , Tehran 's top rival in the region.
The U.S. has recently stepped up its allegations that Iran is arming Shiite militiamen, but the Iraqi government has taken a low-key stance without outright backing the American claims, which Tehran denies. One al-Maliki adviser, Sami al-Askari, said last month that the government "doesn't rule out" Iranian arming of militants.
In Baghdad , meanwhile, U.S. troops and warplanes struck suspected militants in the Shiite district of Sadr City , killing 32 of them and detaining 12 others. The U.S. military said the militants were involved in smuggling weapons from Iran and sending militiamen to Iran for training, informs Mercury News.