BAGHDAD, Iraq - Militants fired mortar rounds at the airport and two roadside bombs exploded today, hours ahead of a signing ceremony for the country's interim constitution, a key landmark in U.S. plans to hand over power to Iraqis by June 30. No injuries were reported.

The signing of the document, scheduled for this afternoon amid tight security, was delayed for nearly a week - first by tough negotiations among members of the Iraqi Governing Council that went beyond a Feb. 28 deadline, then by a three-day mourning period following two suicide attacks Tuesday that killed scores of Shiite pilgrims on the holy day of Ashoura.

The top U.S. administrator, L. Paul Bremer, and chief British representative Jeremy Greenstock mediated with council members through the night in a marathon session that sealed the deal around dawn Monday. Compromises were struck on some of the toughest issues, particularly the role of Islam and federalism.

The draft recognizes Islam as a source of legislation. In a concession to religious conservatives who wanted Islam to be the main source, it also states that no law will be passed that violates the tenets of the Muslim religion.

It also accepts the principle of federalism but leaves it to a future elected national assembly to decide the details of self-rule for Iraq's Kurdish minority.

Delegates hammered out a system that would allow any of Iraq's 18 provinces to form federal regions - a provision opening the door for Shiites to form a self-rule region in the south similar to the Kurds' region in the north.

The U.S.-based rights group Human Rights Watch criticized the document today, saying it does not do enough to protect women's rights, particularly in the area of family law.

"Equal rights for Iraqi women in marriage, inheritance, and their children's citizenship should not be left in jeopardy," said LaShawn R. Jefferson, executive director of the Women's Rights Division of Human Rights Watch. "The interim constitution should explicitly guarantee these rights."

Hours ahead of Friday's signing ceremony, militants fired mortar rounds at Baghdad International Airport, the U.S. military said. A pair of bombs also exploded on capital roads frequently used by U.S. troops, but no injuries were reported.

The United States will transfer sovereignty to the Iraqis on June 30 - though it has yet to be decided how to pick the government that will take power. U.S. troops, however, will only gradually transfer security duties to Iraqi police and civil defense.

Tuesday's bombings of Shiite shrines in Baghdad and Karbala raised the specter of sectarian war. The Governing Council said 271 people were killed in the attacks, while the U.S. coalition said 181 people were killed and another 573 were wounded.

U.S. officials pointed to Abu Musab al-Zarqawi, a Jordanian militant with al-Qaida links, as the prime suspect.

But some officials said the role of foreign militants in the attacks was still unclear.

Bremer said Thursday it was "increasingly apparent" terrorism was coming from outside Iraq, but some American generals were far less certain about the extent of foreigners' roles.

The brutality and sophistication of Tuesday's bombings in Karbala and Baghdad pointed to a foreign influence on an insurgency that is still mainly homegrown, said Brig. Gen. Martin Dempsey, commander of the 1st Armored Division, which controls Baghdad.