US-led forces have been encountering pockets of stubborn resistance as they press ahead towards the Iraqi capital Baghdad.
In one of the longest-running challenges so far in the conflict, air strikes were called in on the southern port town of Umm Qasr to overcome about 120 Iraqis - including suspected elite Republican Guards - firing against US forces.
US aircraft have also bombed Iraqi positions in Nasiriya further north where an estimated 500 Iraqis - using tanks and mortars - stopped US Marines trying to secure a route through the town.
Coalition forces say they have advanced half-way to the Iraqi capital, and have been involved in clashes near the holy town of Najaf in the desert just 160 kilometres (100 miles) south of the city.
In Baghdad - which is being hit by fresh air strikes - senior Iraqi officials have been holding news conferences, praising the Iraqi "heroes" and vowing to punish the "mercenaries" once they reach towns.
At least 77 people have been killed in the southern city of Basra and 366 wounded, they said.
Coalition officials have confirmed that the city was bombed on Saturday night - but a UK spokesman said the reported casualty figure "cannot be right".
Iraqi Vice-President Taha Yassin Ramadan said Iraqis had captured 35 American prisoners of war, and promised to produce them for the television cameras later on Sunday.
But US officials say none of their soldiers have been seized.
The final hours of the battle for Umm Qasr were shown live on television.
The pictures show tanks and then a US Marine Harrier jet bomb the building where the Iraqis were holding out, and firing from the compound stop.
It is not known how many Iraqis were killed.
The battle had been going on for more than 36 hours after US forces secured the harbour - Iraq's only deep-water port.
Coalition forces have so far been unable to use the port.
Iraq's Information Minister Mohammed Saeed Al-Sahaf praised Iraqi "heroes" at Umm Qasr saying US and UK "mercenaries" were in for "shock and awe" - using the coalition term for the tactics being used in the war against Saddam Hussein.
In other developments:
- Iraqi authorities search the Tigris River in Baghdad for what witnesses say was a coalition pilot ejecting over the city - but coalition spokesmen say no pilot is missing
- A British RAF Tornado aircraft is missing after failing to return from a mission, central command in Qatar says. British military sources said it may have been shot down by US Patriot missile batteries.
- British intelligence reports suggest Iraqi President Saddam Hussein emerged alive from the initial US air raid on Baghdad but left the area in an ambulance, Foreign Office Minister Mike O'Brien says
- In northern Kuwait, one US soldier is killed and 12 others injured in a grenade attack at a US military camp; the main suspect - a US soldier - is arrested
- Four heavy bombs are dropped by US planes in northern areas controlled by the militant Islamist group Ansar al-Islam, which is suspected of having links with Osama Bin Laden's al-Qaeda network
- The Pentagon says the US is having discussions with some Iraqi leaders, urging them to capitulate.
- The Pentagon also says that Iraq has not fired any
Scud missiles so far - and US forces have found no caches of weapons of mass destruction.
Baghdad was spared intensive bombing overnight, but bombing resumed again after 1200 GMT with a series of huge explosions - two near the city centre.
Large numbers of US troops are moving towards the capital in a three-mile-long column from Basra.
The BBC's Rageh Omaar says the city is shrouded by a choking black haze from Iraqi fires lit to confuse the coalition planes.
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But US forces have been halted by Iraqi troops about 70 km (45 miles) south-east of Najaf after about two hours of fighting.
Iraqi television said the local Ba'ath Party leader had been killed in the fighting.
It is the closest ground fighting to Baghdad since the war began on Thursday.
Minister Al-Sahaf said 106 civilians had been injured so far in Baghdad.