"The Secretary-General is extremely concerned about the heightened violence in Iraq, which is overwhelmingly aimed against the civilian population," a statement issued by Mr. Annan's spokesman said.

"He is appalled by the latest series of bombings yesterday in Balad that killed more than 90 people and wounded many more, including many women and children, and another serious attack today in Hilla," it added. "No cause can justify such acts of terror."

Noting that the attacks appeared to have been coordinated so as to kill and injure as many innocent civilians as possible, Mr. Annan said those who refuse to participate in the political process should not, by acts of intimidation and violence, deprive others of their right to do so.

"He once again urges Iraqis of all persuasions not to be deterred by such violence and to express themselves peacefully through the democratic process, starting with the forthcoming national referendum on the draft permanent constitution," the statement concluded.

"The United Nations remains committed to working with all Iraqi communities and political entities in supporting the peaceful political transition of their country."