BAGHDAD, Iraq (CNN) -- Iraq's prime minister plans to visit Iran next week to discuss security and other issues with Iranian President Mahmoud Ahmadinejad, a government official said Tuesday.
Iranian President Mahmoud Ahmadinejad, right, visits Iraqi Prime Minister Nuri al-Maliki in Baghdad in March.
Prime Minister Nuri al-Maliki is making his second trip in a year's time to neighboring Iran. The visit comes amid growing concerns among Iraqis and Americans that Iranian agents are training and arming Shiite militants in Iraq.
The visit will be his third trip to the country as prime minister. He visited Iran in September 2006 and again in August.
According to Iran's state-run Islamic Republic News Agency, Abu Heidar al-Sheikh, Iraqi ambassador to Iran, told reporters the trip will last two days and will focus in part on strengthening political and economic ties between the two countries.
The news agency paraphrased al-Sheikh as saying that al-Maliki also would "confer with the supreme leader of the Islamic revolution Ayatollah Seyyed Ali Khamenei on [the] security pact between Iraq and the U.S."
The U.S. and Iraq are trying to reach a bilateral agreement on how long the U.S. military will remain in Iraq and what role it will play in the country's security.
Al-Maliki formed a committee last month to document what Iraqi officials call Iranian "interference" in Iraqi affairs.
The move came after an Iraqi delegation confronted Iranian officials in Tehran with evidence that Iran is smuggling weapons into Iraq and training Iraqi militants. The Iranians vehemently denied the assertions.
American military officials have said Iranian support for "criminal" Shiite militias battling Iraqi and American troops in Baghdad has begun to alarm the Iraqi government.
The U.S. government believes the Islamic republic's Revolutionary Guard Corps' Quds Force has been training militias and providing weaponry, such as the explosively formed penetrator roadside bomb.
The predominantly Shiite Iran has long-standing ties to Iraq's Shiite parties, including the Supreme Islamic Council of Iraq. It is the main party in the United Iraqi Alliance bloc that dominates the country's security forces.
Since late March, the Shiite-dominated Iraqi government has launched military offensives in Shiite regions, including the southern city of Basra and Baghdad's Sadr City neighborhood, and has confronted fighters thought to have backing from Iran.
Al-Maliki's trip follows the visit to Iran last week of Adel Abdul Mahdi, Iraq's Shiite vice president. He met with Ahmadinejad and other top officials and discussed bilateral relations and security issues.
Al-Maliki also plans to visit Jordan.
News of al-Maliki's visit to Iran emerged as U.S.-led coalition troops on Tuesday seized three wanted militants in Sunni and Shiite regions of Iraq.
Troops arrested a wanted militant believed to be "one of the top criminal leaders" in a largely Shiite city southeast of Baghdad, the U.S. military said.
The arrest of the "Special Groups" leader and five associates took place in Kut, a city in Wasit province -- a region that borders Iran. Special Groups is the term the U.S. military gives to Iranian-backed militants.
The man is suspected of involvement in the killing of Iraqis and attacks on coalition troops. He and the five others were arrested without incident.
Also, troops in the northern city of Mosul captured a wanted man and four of his associates. He is suspected of being a security leader for al Qaeda in Iraq, the Sunni militant group, and "is suspected of coordinating bombings against Iraqi police."
Iraqi and American forces have been engaged in an offensive against al Qaeda in Iraq in Nineveh province, of which Mosul is the capital. The area, which is ethnically and religiously mixed, is largely Sunni.
Another wanted man captured in Tikrit, a largely Sunni area in Salaheddin province north of Baghdad, is suspected of aiding the "staging of suicide bombings and foreign terrorist movement for al Qaeda in Iraq."
CNN's Mohammed Tawfeeq contributed to this report.