Updated

International organizations continued their exodus from Iraq, with the United Nations (search) announcing it was withdrawing staff from Baghdad following this week's string of car bombings in the capital and attacks against coalition troops.

The withdrawal orders came despite assurances by top U.S. administration officials, including President Bush, that the security situation in Iraq was steadily improving. It also followed a personal appeal by Secretary of State Colin Powell (search) to the international Red Cross (search) to remain in Baghdad because "if they are driven out, then the terrorists win."

The U.N. decision to pull its remaining international staff out of Baghdad was announced on Wednesday, two days after a deadly car bombing at the Baghdad headquarters of the Red Cross.

"We have asked our staff in Baghdad to come out temporarily for consultations with a team from headquarters on the future of our operations, in particular security arrangements that we would need to take to operate in Iraq," U.N. spokeswoman Marie Okabe said.

She said it was not an "evacuation" and staff in the north would remain.

Okabe declined to give more details but about 60 U.N. staff members were believed to be in Iraq, including some 20 in Baghdad, after Secretary-General Kofi Annan ordered most others out in late September.

The United Nations scaled down its staff following the Aug. 19 truck bombing at its Baghdad headquarters that killed 23 people, including the top U.N. envoy to Iraq, Sergio Vieira de Mello, and a smaller blast near the U.N. offices last month.

Also Wednesday, the International Committee of the Red Cross and the humanitarian group Medecins Sans Frontieres, or Doctors Without Borders, said they too were pulling their workers out of Baghdad despite pleas from the U.S. administration to stay.

The Red Cross said it would remain in Iraq but would scale back the number of international staff — now numbering about 30 — and increase security for those who stay. The agency has 600 Iraqi employees.

U.S. military authorities in Iraq said Wednesday that American forces were now suffering an average of 33 attacks a day — up from about 12 daily attacks in July. A total of 117 American soldiers have been killed in combat since May 1 — when Bush declared an end to major fighting — or slightly more than the 114 soldiers who died in invasion that began March 20.

The violence continued with an apparent assassination attempt Wednesday night against an assistant of Iraq's most influential Shiite Muslim cleric, Grand Ayatollah Ali Hussein al-Sistani, spiritual leader of most of Iraq's Shiite majority.

Sistani's office in the city of Najaf said Thursday they had no details on the attack on the cleric in the nearby city of Karbala and would not give his name. The Baghdad newspaper al Zaman identified him as Abdel Mehdi al Karbali.

Meanwhile, a soldier from the 2nd brigade of the 101st Airborne Division was slightly injured early Thursday when a bomb exploded near a U.S. convoy in the northern city of Mosul, the military said.

In Tikrit, U.S. soldiers raided six houses after receiving "reliable intelligence" that the inhabitants were helping to establish a "new terrorist network in Tikrit and planning terrorist attacks against coalition forces," Lt. Col. Steve Russell told The Associated Press.

Four key suspects were detained, and 10 others were taken in for questioning, Russell said. Coalition troops discovered false identification cards and multiple fake license plates with "official government stickers" in one of the houses, he added.

"We continue to work against these cells, to disrupt, capture or kill them," he said.

The area around Tikrit, about 120 miles north of Baghdad, has been the scene of increased attacks that U.S. troops blame on die-hard supporters of ousted leader Saddam Hussein and members of his Fedayeen militia.

Baghdad police commander Maj. Gen. Hassan al-Obeid also announced measures to bolster security in the capital, including additional 24-hour checkpoints and special patrols around sensitive locations, according to coalition-run Iraqi television.

The Iraqi Governing Council, meanwhile, called on neighboring nations to crack down on infiltrators crossing into Iraq and provide Iraqi authorities with information about former regime figures who may be hiding on their soil.

The council "requests Iraq's brotherly neighboring countries to adopt a clear stand concerning those criminal acts that target Iraqi citizens and their civilian and security establishments, and their political and religious dignitaries," a statement said.

Separately, Mohammed al-Jibouri, head of the State Oil Marketing Organization, said bad weather has delayed Iraq's crude exports from its southern oil terminal for the past three days.

Iraq, which used to sell about 2 million barrels a day before the war, is now exporting around 1.2 million barrels a day from its offshore Basra oil terminal in the Gulf.

The country has so far failed to resume exports from its northern oil fields because of a series of explosions and fires in a pipeline linking the fields to the port of Ceyhan in Turkey.