A U.S. Air Force warplane dropped four enormous bombs Monday on a residential complex where US military sources claim that "extremely reliable" intelligence indicated that Iraqi President Saddam Hussein and one or both of his sons were attending a meeting. The sources would not rule out the possibility that Saddam could have moved before the bomber struck, but they said it was likely that he and his sons were dead.

Based on information from an intelligence source on the ground in Baghdad, U.S. military officials were confident that Saddam and his son Qusay were attending a meeting in the neighborhood with other top Iraqi leaders.

Senior U.S. officials have told a news agency that Saddam's likely successor, assuming Qusay Hussein was not available to take command, would be Izzat Ibrahim, vice chairman of the Revolutionary Command Council. The sources said Ibrahim was believed to be in Mosul in northern Iraq in recent weeks, not in Baghdad.

Battles Fought in the Heart of Baghdad

Correspondents say US troops are in the heart of Baghdad after raiding Saddam Hussein's main palace and battling Iraqi forces on Monday.

Four US tanks remained inside the palace compound, and were involved in fierce exchanges early on Tuesday.

The tanks advanced under fire from Iraqi positions, as low-flying US planes provided air support.

A correspondent from Reuters news agency says the tanks appeared to be moving towards other government buildings to the north, in an apparent effort to expand the area controlled by US forces.

South of Baghdad, the US military says initial field tests on chemicals found near the city of Karbala suggest the possible presence of the nerve agents sarin and tabun, as well as mustard gas.

The Pentagon has cautioned that these are only preliminary results and further laboratory tests will be conducted. Defence Secretary Donald Rumsfeld said that could take days.

There have already been a series of false alarms about a "smoking gun" since the invasion of Iraq began and coalition forces started searching for weapons of mass destruction.

Jazeera TV Office Hit in Baghdad Air Raid, Tariq Ayoub Killed

Al-Jazeera television said on Tuesday its Baghdad office was hit by a U.S. missile during an air raid on the Iraqi capital and that two of its staff were wounded, one of whom, Tarek Ayoub, died later of his wounds

Jezeera's Baghdad correspondent Maher Abdullah said the missile strike destroyed an electricity generator and set fire to the Arab satellite TV's office.

Jazeera said their other wounded staff is called Zohair al-Iraqi.

Earlier, Reuters correspondent Samia Nakhoul said U.S. planes were bombing targets near the ministry.

Footage from fellow Arab network Abu Dhabi TV showed a fire blazing in the Jazeera office, which is in a multi-story building near the ministry of information. Jazeera correspondent Tayseer Alouni, who made his name covering the U.S.-led war on Afghanistan, was seen carrying a wounded colleague into an Abu Dhabi TV car.

The Qatar-based network, which is one of the most widely watched in the Arab world, has come under intense criticism by U.S. and British officials for showing images of slain Western soldiers and U.S. prisoners of war.

PHOTO CAPTION

People stand amid rubble in Baghdad's Mansour neighborhood after a U.S. air strike.