Iraqi Information Minister Mohamed Said al-Sahhaf denied claims by US commanders, and reports from AFP journalists on the ground with US troops, that American forces were now on the outskirts of Baghdad and very close to the city's airport.

He told a press conference here that US troops were "not even 100 miles" from Baghdad, but said Thursday's air strikes in and around the city had killed 27 civilians and wounded 193.

A statement attributed to President Saddam Hussein and read on state television said Iraqi forces would never let the capital be taken.

"Many thousands of soldiers are defending the homeland ... and they will not allow them to go into Baghdad without defeating and repelling them," the statement vowed.

It said barely a third of Iraq's forces had yet been engaged in battle.

But US officers said 500 Iraqi troops were killed in clashes with US forces for a key bridge some 30 kilometers (20 miles) southwest of the capital, while other US soldiers were just half that distance from downtown Baghdad.

Major General Buford Blount, commander of the 20,000-strong US infantry division at the city's edge, said the US military now controlled the southern approaches to the capital.

Iraq has repeatedly warned that the war's decisive battle will be in Baghdad, where it could engage US-led forces in bloody street-to-street fighting. It also says it has thousands of volunteers ready to become "martyrs" in suicide strikes.

AFP reporters in Baghdad since the war began said the bombardment of the city has been stronger in recent days and that on Thursday afternoon it was unusally heavy. Massive explosions boomed from the southern outskirts.

Saddam's elite Republican Guard forces are said to be outside the city to the south, defending the capital from US and British troops who have been sweeping northward since entering Iraq from neighbouring Kuwait.

Iraq denies US claims that two Guard divisions have been devastated by the air assault, which US commanders say has been intended to weaken the dug-in units of the 60,000-strong Guard.

The Pentagon said the Guard's Medina and Baghdad divisions are no longer "credible forces." At the US Central Command forward base in Qatar, Brigadier General Vincent Brooks said the Baghdad division "has been destroyed."

An Iraqi military spokesman said the claim was baseless and told AFP that the Baghdad division "has a morale of steel."

More and more trenches filled with oil have been set ablaze around the city in an effort to hamper the visibility of coalition pilots, giving off thick black clouds and rendering the air noxious.

US Central Command announced that a naval F/A 18 Hornet fighter had gone down over Iraq on Wednesday. A US Army Blackhawk helicopter was also shot down.

The US-led coalition launched at least two attacks on Baghdad's Republican Palace, the third straight day the sprawling complex on the Tigris river was bombed.

US Central Command said coalition forces targeted the presidential bunker and residence along with the New Presidential Palace in the Al-Khark section west of the Tigris.

Warplanes also struck a farm used as a command and control post southwest of Baghdad and a military store in the Iraqi capital, Centcom said.

The US and British bombing has racked up mounting civilian casualty tolls. Iraq said 10 people died and nearly 90 were injured Tuesday, and that a Red Crescent maternity clinic was flattened Wednesday, killing at least one person.

"We've worked very hard to avoid civilian deaths and casualties," British Foreign Secretary Jack Straw told Indian television on Thursday.

"There will be some, very sadly, but I believe that once this military action is over the total number of civilian deaths and casualties would have been shown to be relatively small," he said.

Iraqi state television has been regularly targeted in air strikes by the United States, which believes repeated broadcasts of a confident regime crushing the invaders are key to maintaining Saddam's grip on power.

The New York Times on Thursday quoted a senior official saying that Washington's refusal to say whether it knows Saddam is alive was part of an intentional campaign to sow doubt in the minds of Iraqi commanders in the field.

"You could call this psychological warfare, or you could call it exploitation of the biggest mystery out there," the official said.

SPACE.WIRE