The most influential politician in Iraq issued a veiled warning Wednesday to Sunni Arabs that Shiites would not allow substantive amendments to the country's new constitution, including to the provision that keeps the central government weak in favor of strong provincial governments.

Abdul Aziz al-Hakim, the leader of the Supreme Council for the Islamic Revolution in Iraq, or SCIRI, said in an address in honor of the Islamic holiday of Eid al-Adha that provincial governments will remain strong in the constitution, which can be amended after the next government is installed.

"The first principle is not to change the essence of the constitution. This constitution was endorsed by the Iraqi people," he said.

Sunni Arabs place great stock in their ability to change the constitution, one of the reasons Sunni politician urged the minority to turn out in large numbers during the Dec. 15 parliamentary election.

They want a stronger central government because the constitution now bestows most power — including control over oil profits — to provincial governments.

The Shiites in the south and the Kurds in the north control most of Iraq's oil. There are few oil reserves in central Iraq, where Sunnis live.

To win their support for the new constitution, which was approved in an Oct. 15 vote, Sunni Arabs were promised they could propose amendments to it during the first four months of the new parliament's tenure. The new parliament is expected to be seated around the end of February. Amendments need two-thirds approval in parliament and a majority in a national referendum.

There was limited violence Wednesday. A roadside bomb exploded next to a police patrol outside Samarra, about 60 miles north of Baghdad, killing two policemen, police Capt. Laith Mohammed said.

Iraqi police found seven bodies shot in the head, their legs and hands bound, in a sewer in eastern Baghdad, 1st Lt. Mohammed Khayon said.

Meanwhile, health officials in northern Iraq, which shares a border with Turkey, have started taking measures to prevent possible cases of bird flu from entering the country. Preliminary tests have shown that at least 15 people in Turkey have been infected with the deadly H5N1 strain of the flu. Two children have died.

Doctors, veterinarians and other health ministry officials met Sunday in northern Iraq's Kurdish enclave to discuss bird flu, the region's minister of agriculture said Wednesday.

"A campaign will start on the borders of Turkey and Iran to prevent the importation of any kind of bird," Shamal Abid Waffal said. "No living birds are allowed to be sold in the markets. Even the frozen birds are not allowed to be taken from one city to another without medical tests."

There have been no reported cases of bird flu in Iraq.

Iraqis nationwide celebrated the opening of the four-day Eid al-Adha celebration on Tuesday with visits to relatives, food and sweets. Lambs were slaughtered and food was distributed to the poor.

Eid al-Adha — one of Iraq's biggest holidays — concludes the pilgrimage to Mecca and is celebrated by Muslims worldwide. It commemorates Abraham's readiness to sacrifice his son in God's test of the patriarch's faith. At the last moment, God substituted a sheep for the son.

The story is shared by the three "Abrahamic" religions — Islam, Judaism and Christianity — although Islam says the son in question was Ishmael, while Judaism and Christianity maintain it was his brother Isaac.

Shiites and Sunni Arabs also called for an end to the bloodshed that has wracked Iraq since last month's elections.

"This Eid is a happy day for all Muslims, especially Iraqis. But it comes after painful events that happened in Karbala and Ramadi," said Prime Minister Ibrahim al-Jaafari, a Shiite.

He referred to the killings of more than 120 people in suicide bombings last week in the Shiite holy city of Karbala and at a police recruiting center in Ramadi.

On Monday, homicide bombers infiltrated the heavily fortified Interior Ministry compound in Baghdad and killed 29 Iraqis — an attack claimed by Al Qaeda in Iraq, a group with an avowed aim of starting a sectarian war.

Violence has increased since the Dec. 15 elections, with at least 498 Iraqis and 54 U.S. forces killed.

Al-Jaafari said despite the violence, Iraq had made significant advances in 2005, citing a large turnout in Dec. 15 elections as one of the biggest achievements.

About 70 percent of Iraq's 15 million voters, including large numbers of Sunni Arabs, participated in the elections, although some Sunni Arab groups complained the vote was tainted by fraud — delaying the release of results.

Al-Jaafari's governing United Iraqi Alliance emerged with a large lead in the elections, far ahead of a Kurdish coalition and Sunni Arab groups but without the majority it will need in the 275-member parliament to avoid a coalition.

With final results expected next week, the Shiites, Kurds and some Sunni Arab groups have been talking about forming a broad-based coalition government.

Al-Hakim, the leader of the United Iraqi Alliance, urged Sunni Arabs on Tuesday to stop complaining and accept the results.

In Washington, President Bush, speaking at a gathering of the Veterans of Foreign Wars, also urged Iraqis to put aside their differences to form a government of national unity, warning that the country "risks sliding back into tyranny" if it dwells on old grievances.