US tanks and armoured vehicles have launched their first raid into Baghdad city - and fought skirmishes with Iraq's elite Special Republican Guard, US officials say.
Abrams tanks led the raid
Two task forces went up to the Tigris river from the southern outskirts of the city before moving west towards the airport, Major General Victor Renuart told a news briefing at US central command in Doha, Qatar.
General Renuart said the intention was to indicate to the Iraqi leader that coalition forces could move in and out of Baghdad whenever they wished.
Earlier, a US spokesman described the operation as the beginning of "rolling patrols".
BBC correspondents say they have not seen US troops in the centre of Baghdad.
Meanwhile President Saddam Hussein has urged the Iraqi army and people to step up their attacks on US and UK forces, according to a statement read out on state television.
In other military developments:
- US troops and aircraft have launched an attack on the city of Karbala, some 60 kilometres (37 miles) south of Baghdad.
- The US Army is reported to have captured the Suwayra headquarters of the Republican Guard's Medina Division, but a military official in Doha could not confirm.
- American B-52 bombers attack Iraqi positions about 10 km north of the northern city of Mosul.
- US rangers and special forces are reported to have taken control of the road leading to Tikrit - the birthplace of the Iraqi president - to the immediate north of Baghdad.
- In Basra, British forces say they are moving further into the city and have destroyed a building where one of Iraq's most important military commanders, Ali Hassan al-Majid - also known as Chemical Ali - was thought to be staying.
The BBC's Rageh Omaar, whose activities are restricted by authorities, witnessed the evidence of recent fighting littering the main roads, with Iraqi tanks and armoured personnel carriers still on fire.
Truckloads of Iraqi troops, some towing howitzers, and heavy Iraqi artillery were seen moving on the streets of Baghdad for the first time since the conflict started.
Police cars, their sirens blaring, have been broadcasting messages of defiance.
What appeared to be small-arms or mortar fire was heard from the direction of the suburb of Yarmuk.
General Renuart said the troops that launched the raid had faced sporadic resistance from mixed Iraqi irregulars and Special Republican Guard using anti-aircraft weapons.
Iraqis have deployed heavy armour in the centre of Baghdad
Iraqi Information Minister Mohammed Saeed al-Sahaf denied the incursion, saying Iraqi forces had expelled US troops from the city's international airport and inflicted heavy losses on the Americans.
But the US general said the airport was secure and would be made operational very soon.
Earlier, Iraqi officials said their people were preparing "unconventional" attacks to reconquer the airport, which coalition forces took on Friday, raising the spectre of an urban battle with possible suicide squads.
In Saturday's statement, President Saddam Hussein called on Iraqis to "raise the level of your attacks" against coalition forces which, whilst focused on Baghdad, were weakening elsewhere.
However, correspondents say the message - read out on television by the information minister - will further fuel speculation about the Iraqi leader.
On Friday, Iraqi television showed footage of
President Saddam Hussein meeting cheering residents on the streets of Baghdad.
Western experts are studying the television film of the Iraqi president in military uniform to try to determine if it is Saddam Hussein.
The Iraqi leader is believed to use doubles for security reasons.
In other developments:
Three Iraqi diplomats are expelled from the Turkish capital, Ankara, because they had been carrying out "duties incompatible with their status"
HAVE YOUR SAY
This battle will be won by America and its allies at a great cost to innocent Iraqi people
Mohammad Shoaib, Delhi, India
- British forces in southern Iraq have discovered hundreds of human remains in an abandoned military base on the outskirts of al-Zubayr.
- The International Committee of the Red Cross said several hundred wounded Iraqis have been admitted to Baghdad hospitals since US troops reached the city and fighting erupted.
- President George W Bush vows to treat as war criminals members of the Iraqi regime "terrorising its own citizens, doing everything possible to maximise Iraqi civilian casualties, and then to exploit the deaths they have caused for propaganda".
- A US soldier - Sergeant Hasan Akbar of the 101st Airborne Division - is charged with murder in connection with a grenade attack at a US military camp in Kuwait last month which killed two officers.