"We, the Armed Vanguards of the Second Muhammad Army, claim responsibility for the bombing of the UN headquarters. We say it proudly that we did not hesitate for one moment to kill Crusader blood," read a typewritten, Arabic statement that Al-Arabiya TV broadcast.
The statement included a pledge "to continue fighting every foreigner in Iraq and to carry out similar operations".
Such statements from several self-proclaimed fighting forces have appeared often in the Arab media in recent months. US military officials say it is difficult to determine whether any of the groups exist beyond their videotapes and written statements and which are responsible for attacks on coalition troops and, increasingly, civilian targets in Iraq.
The UN began pulling a third of its staff out of Iraq yesterday as three more bodies were pulled from the rubble of its shattered headquarters.
The grim discovery in Baghdad brought the death toll from Tuesday's massive truck bombing to 23.
A UN spokesman said about 100 support staff were being flown out of Iraq to Amman in Jordan and Larnaca in Cyprus following the bombing.
Romiro Lopez da Silva, Iraq co-ordinator for UN humanitarian programmes, said 86 UN staff members had been seriously wounded in the attack and were being flown out of the country as their condition allowed.
He said two of his UN colleagues were still unaccounted for and an unknown number of people, visitors to the headquarters building, were still buried under the rubble.
Hundreds of soldiers and civilians, helped by sniffer dogs, picked through the remains of the Canal Hotel, which had housed the UN offices. All evidence of human remains was being collected and would be sent to a lab for testing, said David Roath of the US Defence Department, who is overseeing the recovery efforts.
Among the dead was the UN's chief envoy to Iraq, Sergio Vieira de Mello.
FBI agents have said the bomb was made up of 1,000lbs of ordnance, including mortar rounds, artillery shells, hand grenades and one 500lb bomb.
The explosives were piled on a Soviet-made military flatbed truck known as a KAMAZ. The vehicle was driven to a wall recently built around the hotel and detonated. Some munitions failed to explode, and investigators and rescue workers dug through the site carefully to avoid setting them off.
Paul Bremer, the top US official in Iraq, said there were "at least two hypotheses" about the bombing one blaming remnants of the Saddam regime, and the other insurgents from neighbouring countries.
Elsewhere, the hunt for Saddam continued with a raid on a farm in the northern town of Abbarah. Soldiers captured five men but the former dictator was not among them.