Iran has closed its major border crossings with the Kurdish region of northern Iraq, in protest at the arrest of an Iranian by US forces there.
He was detained on suspicion of smuggling sophisticated roadside bombs to militias fighting US troops.
Separately, police in northern Iraq say at least six people have been killed in a suicide bombing.
Seventeen people were wounded in the explosion at a security checkpoint near the city of Mosul.
An Iraqi journalists' group, the Freedom for Journalists Association, says an Iraqi television presenter working for a private channel, al-Baghdadiya, has been shot dead by gunmen in the capital Baghdad.
US military officials in Iraq say that the Iranian detained on 20 September is a member of Iran's Revolutionary Guards and that he was involved in smuggling explosives.
But Iran, the Kurdish regional government, and the Iraqi president, Jalal Talabani, say he was a member of a visiting trade delegation and have demanded his release.
The Kurdish regional government said it was concerned about the border closure, which it said was punishing local people for something that the Americans had done.
The governor of the neighbouring Iranian province of Kurdistan said Iran hoped that the Iraqi authorities would act as quickly as possible to secure the man's release.
The US has accused the elite Quds Force of Iran's Revolutionary Guards of helping arm Shia militias in Iraq. Iran denies any involvement with militants.
It is the second such incident in Iraqi Kurdistan this year.
Tehran is still demanding the release of five Iranians seized in the city of Irbil in January who the US says have links to the Revolutionary Guard and were training militants in Iraq.
In August, the US military admitted to what it called a "regrettable incident" after it arrested a group of eight Iranians in Baghdad. They were freed after the Iraqi government intervened.