Demands for reform of the PUK are likely to dominate the meeting, due to last several days, as it faces an upstart opposition movement and a loss of ground to the Kurdistan region's other leading bloc, the Kurdistan Democratic Party (KDP) of regional president Massud Barzani.

"Today was a good start, and I expect that it will be a successful conference," said Fareed Asasart, a senior PUK official.

"There will be more opportunities for young members to take part in the leadership of the PUK, and there is a quota for women as well."

Prime Minister Nuri al-Maliki, Vice President Adel Abdel Mahdi and Ammar al-Hakim, the head of a major Shiite political party, all attended the first day of the congress, which comes as parliamentary factions hold coalition talks nearly three months after a general election.

The PUK fielded candidates in alliance with the KDP and between them they won 59 seats, making them the fourth largest bloc in the Iraqi parliament.

The congress is only the third held by the PUK since its inception -- the previous two were immediately after its founding and then following the US-led invasion that ousted Saddam Hussein in 2003.

Disenchantment in PUK ranks prompted a group of defectors to form a new party called Goran (Change in Kurdish) last year.

The breakaway group has already made a significant dent in the PUK's traditional power base in Iraqi Kurdistan's second city of Sulaimaniyah.

That has eroded the position of the PUK vis-a-vis the KDP, headed by Talabani's adversary-turned-ally Barzani, and the PUK is now clearly the junior partner in the Kurdish alliance.