Powerful Shiite politician Abdel Aziz al-Hakim returned to Iraq's holy city of Najaf on Friday after receiving treatment for cancer in Tehran.
Hakim, the head of one of the most powerful parties in the parliament, spent nearly two weeks abroad in a trip that included medical tests in the United States and treatment in Iran.
"He is in his headquarters in Najaf and will be there for a long time, after he finished his initial period of treatment in Tehran," said Muayyad al-Hakim, secretary of the politician's son Ammar.
Two weeks earlier, Hakim, 57, flew to the United States for medical tests before travelling on to Tehran.
On May 22, Hakim's son, Ammar, said in Najaf that the health of his father was "stable and the doctors in America confirmed to him that the cancer tumour is limited and could be brought under control."
In Tehran, Hakim's other son, Mohsen, told AFP on Friday that doctors "found swelling in one of his lungs, but his general condition is fine and there isn't any special problem."
He confirmed that his father was now back in Iraq.
Hakim's Supreme Islamic Iraqi Council (SIIC), formerly known as the Supreme Council for the Islamic Revolution in Iraq, was founded in Iran in 1982 as an opposition movement in exile.
The party returned to Iraq in the aftermath of the March 2003 US-led invasion. It joined Prime Minister Nuri al-Maliki's beleaguered coalition government last year after winning 30 seats in the 275-member parliament.
Hakim's illness comes as one of his main rivals, radical Shiite cleric Moqtada al-Sadr, has resurfaced after several months in hiding.
Despite SIIC's close ties with Iran, Hakim has tried to build bridges with the United States, and last year met President George W. Bush at the White House.
Tehran has been accused of supplying weapons to both Sadr's Mahdi Army militia and Hakim's Badr Brigade, which was founded in Iran and has now infiltrated many Iraqi security force units.
On February 23, Ammar al-Hakim was detained by US forces in eastern Iraq and held briefly after his road convoy came back over the border from Iran.