US-led coalition forces have bombed Iraqi Air Force headquarters in central Baghdad as US ground troops pressed closer from the south.
In a statement, the US Central Command says the air assaults on the Air Force headquarters west of the Tigris River hurt Iraqi ability to control its air assets.
Pre-dawn blasts also hit many targets in the heart of the capital, including presidential palaces.
Residents still had no electricity or water Friday, after the first widespread power outage of the war plunged Baghdad into darkness Thursday night.
US military officials say they didn't target Baghdad's power grid.
The electricity went out as US forces and Iraqi defenders fought in Saddam International Airport, 20 kilometres southwest of the city centre.
US forces say the Engineer Brigade of the 3rd Infantry Division occupied part of the airport and had sealed the entrance closest to Baghdad.
Military analysts say Saddam International Airport is a key objective for US forces, who can use it as a forward operating base in any battle for Baghdad.
The US military says 320 Iraqi foot soldiers were killed in fighting for control of the airport, and dozens of Iraqi anti-aircraft artillery, troop carriers and trucks had been captured or destroyed.
American forces also reportedly found a network of tunnels beneath Baghdad airport, stretching back to the Tigris river.
In northern Iraq, Kurdish fighters, backed by small groups of US soldiers, advanced toward the northern oil town of Mosul and were met by heavy machine-gun and rifle fire.
Further south, US troops moved into the centre of the Shi'ite Muslim holy city of Najaf, searching for paramilitary fighters. Allied forces also tightened their grip on Nassiriya, where they appeared to be in full control of bridges over the Euphrates.
In the far south, British forces edged further into the outskirts of Iraq's second city of Basra, reportedly capturing an industrial complex where Iraqi militia had spearheaded fierce resistance.
So far, the United States lists 54 dead and 12 missing since the war began. Britain says it has suffered 27 dead.
Iraq has not given figures for military deaths, but Foreign Minister Naji Sabri has said more than 1,250 civilians have been killed since the beginning of the conflict.
Meanwhile, Sabri said Thursday that Iraq will expose to the world the war crimes US and British troops have committed in the country. In a statement to the British Broadcasting Corporation, Sabri said Iraq is now contacting international organizations.
"They are invading forces and they have been committing a lot of crimes against humanity, a lot of war crimes against our population. They have been targeting civilians, civilian houses and buildings, food stores, post office centres, schools, hospitals. They have been targeting all these places. They have been targeting market places and schools. These are war crimes, we are explaining these developments to the world."
In Washington, US President George W. Bush's top military advisors say US forces might isolate Baghdad rather than attack it, in order to give time for a new government to be set up.
Chairman of the Joint Chiefs of Staff, Richard Myers, said Thursday that the plan was to isolate Iraqi leader Saddam Hussein and his inner circle. Myers indicated that the intention is to slowly end the political and military authority of the Iraqi government without engaging in a ground assault that would risk military and civilian casualties.
At the same time, the U.S. Secretary of Defense Donald Rumsfeld ruled out any negotiations with the Iraqi leadership, saying that discussions would only give the Iraqi government another means of prolonging the war and shoring up their military.