Iran pledged on Sunday to help establish security in Iraq and visiting Iraqi Prime Minister Nuri Al Maliki vowed his country would not be used to harm Iran.Some Iraqi officials and the United States have accused Iran of trying to destabilise Iraq by financing, training and equipping Iraqi militias.
Iran blames the instability on the presence of US troops in Iraq.
During Al Maliki's three-day visit to the Islamic state, Iranian officials have insisted Tehran supports peace and security in the neighbouring country.
"Iran will always be on the side of the popular government of Iraq," the state news agency IRNA quoted First Vice-President Parviz Davoudi as saying in talks with Maliki on Sunday.
"Helping the establishment of security in Iraq has always been one of Iran's main policies."
The student news agency ISNA quoted Al Maliki as saying in Tehran: "Iraq's territory cannot be used by any country for harming Iran's security."
An Iraqi spokesman said last week Al Maliki wanted to discuss evidence of Iranian intervention in Iraq and the two countries' overall relationship.