Massud Barzani, the president of Iraq's autonomous Kurdistan, said the Kurds would not compromise on their demands that include a federal Iraq and the incorporation of the northern oil centre of Kirkuk in their autonomous region.
"We will not accept that Iraq's identity is Islamic," Barzani told an emergency session of the autonomous Kurdistan parliament.
He also rejected suggestions that Iraq be termed an Arab nation. "Let Arab Iraq be part of the Arab nation -- we are not," the Kurdish leader said.
Barzani, one of the leaders of the 4.5 million Kurds in Iraq, will take part in a national conference of top Iraqi leaders on Sunday in Baghdad in a bid to break the deadlock on agreeing to a new draft constitution.
"This is a golden chance for Kurds and Kurdistan -- if we don't do what is important for Kurdistan, there will be no second chance. We will not make our final decision in Baghdad, the Kurdish parliament will decide," he said.
The Kurds want a constitution that will guarantee federalism and preserve their region's autonomy, wrested from Saddam Hussein 14 years ago.
Barzani also insisted his region would retain its Peshmerga militias, despite calls by Baghdad that they be incorporated in the national army.
The emergency meeting of the Kurdish parliament prompted a two-day postponement of the national conference to break the constitutional deadlock.
The deadlock revolves around federalism, what the official languages of the new Iraq will be, the relation between religion and state, the rights of women and the future of Kirkuk.
"We are worried about comments from some on the committee," said the regional parliament's speaker, Adnan Mufti, who is also a senior official in the Patriotic Union of Kurdistan, the former rebel group of Iraqi President Jalal Talabani.
Mufti said the Kurds were ready to endorse the charter "if all parties understand a constitution should be based on rights for all Iraqis."
He added: "There is no way to have a unified Iraq without federalism."
Many leaders of Iraq's Arab majority -- both Shiite and Sunni -- have voiced concern that federalism could open the way to secession, although the Kurds insist it is the best way of preventing the breakup of Iraq.
Kurdish hopes of a federal structure for Iraq were boosted Friday after Shiite spiritual leader Grand Ayatollah Ali Sistani gave a favourable response to the idea during a meeting with Prime Minister Ibrahim Jaafari.
"Sistani does not disagree with the principle of federalism if the Iraqi people choose it," Jaafari told reporters after meeting the reclusive cleric at his home in the Shiite pilgrimage city of Najaf.
Iraqi leaders insisted they remained on track to complete a final draft for debate by parliament by August 15 ahead of a referendum in mid-October.
The referendum will be followed by new nationwide elections in December. The national conference is due to report back by August 12, and any matters still unresolved will be put to parliament for decision by majority vote.
As the debate on constitution raged, about 1,000 US marines and Iraqi soldiers combed western Iraq, a region that has emerged as a killing field for marines with 40 US troops dying there in the past fortnight alone.
The latest security operation, code-named Quick Strike, was being conducted in areas of Haditha, Haqliniyah and Barwanah.
The US military claimed some success Saturday saying it had thwarted car bombings in the region after finding three vehicles packed with explosives following a tip-off by a local inhabitant. It said the security forces blew up the cars.
The latest operation led to the death on Wednesday of 14 marines, the largest single combat casualty figure since the March 2003 invasion.
Meanwhile, a British soldier was injured in an attack in the southern city of Basra, London said giving no further immediate details, while at least four Iraqis, including two soldiers and a policeman, were killed in other attacks.
The US military said one soldier died on Thursday in the northern town of Mosul.