The Iranian Government has invited a militant Iraqi Shia leader, Moqtada Sadr, to the country despite warnings from the US that Iran should stop meddling in Iraqi affairs.
By Sadeq Saba
BBC Iranian analyst
The official Iranian news agency said Mr Sadr was visiting Iran to take part in a ceremony to mark the anniversary of the death of Ayatollah Khomeini, the founder of Iran's Islamic regime.
The US is concerned about Iranian influence in Iraq
But there are far wider political implications.
Mr Sadr is one of the most radical Shia clerics in Iraq.
Unlike most other Islamic leaders, he has defended the idea of an Iranian-style theocracy in Iraq.
In his Friday sermons at the Kufa mosque near Najaf, he has repeatedly called for a ban on alcohol and for the veiling of women.
Such statements are music to the ears of Iran's ruling clerics.
[Mr Sadr's] visit to Iran could also mean that the Iranian Government is trying to unite Iraq's rival Shia groups to enable them to have more influence in their country
His armed group, known as Jamaat al-Sadr al-Thani, is believed to have been behind several anti-American demonstrations in Baghdad.
Moqtada Sadr's followers were blamed for the killing in April of a leading Shia cleric, Abdul Majid al-Khoei - a charge he strongly denies.
His group again angered the Shia community by surrounding the house of Iraq's most senior Shia cleric, Ayatollah Ali Sistani, ordering him either to pledge allegiance to their leader or leave the country.
Mr Sadr, who is only about 30 years old, is influenced by Ayatollah Kazem Haeri, a conservative cleric based in the Iranian Shia centre of Qom.
Mr Sadr's visit to Iran could provide further reason for Washington to suspect that Iran is seeking to undermine its military presence in Iraq by supporting militant anti-American clerics.
Mr Sadr has already met Iran's powerful former President, Akbar Hashemi Rafsanjani, and the official Iranian news agency has praised him as one of the most influential Iraqi clerics.
The Sadr group has been at odds with another Iraqi Shia organisation, the Iranian-backed Supreme Council for the Islamic Revolution in Iraq.
So his visit to Iran could also mean that the Iranian Government is trying to unite Iraq's rival Shia groups to enable them to have more influence in their country.