Iraqi Prime Minister Nuri al-Maliki is visiting Tehran Tuesday - his first official visit to the neighboring country since taking office in May.
The prime minister is expected to meet with Iranian President Mahmoud Ahmadinejad and other senior leaders.
A Maliki spokesman Ali al-Dabbagh is quoted by Reuters as saying the prime minister will focus on Iraq's need for security and stability.
U.S. officials have repeatedly said Iran is not doing enough to stop the flow of militants entering Iraq.
Mr. Maliki was to visit Tehran Monday, but an Iraqi official said the trip was delayed by one day for "technical reasons."
Meanwhile, a court in Baghdad is hearing witnesses in the trial of former Iraqi leader Saddam Hussein and six co-defendants accused of ordering the killing of tens of thousands of Iraqi Kurds in 1988.
During Monday's session, a former Kurdish militia fighter Katreen Elias Mikhail testified about a 1987 chemical attack and bombing campaign.
In an outburst, Saddam accused the witnesses of trying to create divisions between Kurds and Arabs.
Saddam has said the offensive in the 1980s - known as the Anfal campaign - was aimed at Kurdish guerrillas who fought his forces alongside Iran.
Prosecutors say the offensive killed 180,000 civilians.
Some information for this report was provided by AFP, AP and Reuters.