United Nations officials in Baghdad say up to one third of its staff is being moved out of Iraq. Officials also say the world body will open a new office Saturday to replace the building devastated by a bomb attack. Senior Iraqi police officials Thursday said the casualty toll from Tuesday's attack has risen to 24 people dead and 86 wounded.

The United Nations humanitarian coordinator for Iraq, Ramiro Lopes da Silva, says at least 100 administrative staff will be moved out of Iraq but they will continue to work to try to rebuild the country.

Appearing before reporters with his head bandaged from injuries sustained in the attack, Mr. Lopes da Silva Thursday said he is working around the clock to open new U.N. offices in Baghdad by Saturday.

He said replacements for those U.N. staff members who were killed or injured in Tuesday's blast are being sent to Iraq.

"We were about 300 in Baghdad as of Tuesday," he said. "We will be 200 from Saturday onwards, and we have colleagues coming in as we speak to start that process of rotating staff." Mr. Lopes da Silva said security for the new U.N. offices would not be increased.

"I felt like we were always at the risk of being at the wrong place at the wrong time," said Lopes da Silva. "I felt like we were always an opportunity target, but I never felt personally or institutionally threatened. And I intend to continue along those lines as we were before last Tuesday."

The Canal Hotel where the U.N. keeps its headquarters, was protected by a platoon of U.S. soldiers and by private security guards trained by the United Nations.

An official for the U.N. Children's Fund, that is based in a separate building across town, said his organization will not stop its work rebuilding schools and setting up children's rehabilitation programs. Spokesman Geoffrey Keele said UNICEF, however, would likely beef up its security. "We are concerned for our own personal safety," he said. "We need to look at our own security measures very closely to ensure our own security as much as possible. And I'm sure changes will be made."

But U.N. officials in Baghdad continue to express determination to carry on as workers remove debris from Tuesday's blast.

In a separate development, the U.S. military announced the capture of the number five Iraqi official on its most-wanted list. The command said that Ali-Hassan al-Majid, a cousin of Saddam Hussein known as Chemical Ali, had been arrested. No further details were provided at the time.

The Iraqi general earned the nickname "Chemical Ali" for his role in chemical weapons attacks against Kurds in 1988 that killed thousands of people.

British military officials said last April they believed Chemical Ali was killed in an air strike in southern Iraq but admitted, after interrogating prisoners seized in the area, that he could still be alive.