A massive convoy of US marines have swept down the main road leading to Baghdad today under the protection of withering artillery and mortar fire, said an Associated Press report.

AP

added that the marines were leading the way to Baghdad amid reports that Iraq's Republican Guard was moving reinforcements south for a showdown.

Meanwhile a Reuters report stated that the advance armored units of the US 3rd Infantry Division were just 10 kilometers from the southern edge of Baghdad.

The news agency also quoted its Baghdad-based correspondent Samia Nakhoul as saying that she heard an intense and sustained anti-aircraft barrage coming from the southern outskirts where US-led forces have been bombarding the city's defenders.

AP

said that Iraqi forces were defending their positions by firing from 155 mm howitzers the town of Numaniyah as the Marine advance resumed.

"While some Marine units had been roughly following the Tigris River, the Army was advancing along the Euphrates River, with some units within 32 kilometers of the Iraqi capital," added AP .

Black Hawk down

Meanwhile a US Army Black Hawk helicopter has been shot down by small arms fire in southern Iraq, killing seven and wounding four o­n board, US officials said today.

The helicopter was shot down near Karbala, about 80 kilometers south of Baghdad, early this morning, news agency Reuters quoted officials as saying.

Shortly afterwards, an F/A-18 Hornet fighter plane crashed over southern Iraq, BBC News o­nline quoted Central Command as saying.

BBC

said that US television reported that the plane was shot down by a missile near Karbala, but Central Command would not confirm that report. The fate of the pilot is not yet known.

The US Central Command had issued a statement a short time later confirming the Navy fighter jet, which is based aboard the USS Kitty Hawk aircraft carrier in the Gulf, was down, but giving no details about the location or the fate of the pilot

Republican Guard made ineffective

On the helicopter crash, Reuters added that search and rescue personnel were at the scene and the four wounded soldiers were rescued.

The Black Hawk was the second US helicopter lost in combat since US and British forces invaded Iraq two weeks ago. An Apache gunship went down last week and its two crew members were captured by Iraqi forces ( photo ).

Kerbala city has seen heavy fighting in recent days between coalition forces and Iraqi Republican Guard units.

Meanwhile CNN reported that coalition forces have pummeled Iraq's Republican Guard, leaving two of six divisions ineffective.

Maj Gen Stanley McChrystal told reporters that coalition forces were moving closer to Baghdad, and that the Republican Guard Baghdad Division and the Medina Division were no longer "credible forces".

Difficult battles ahead

At the same time, both McChrystal and Pentagon spokeswoman Victoria Clarke stressed the most difficult battles may yet unfold.

"As much as we are making good progress -- and we are -- the toughest fighting could lie ahead," Clarke was quoted as saying. "The likelihood that they might use chemical weapons is in front of us now. We are not underestimating how tough it could be going forward."

CNN

said that the US ground forces closed in o­n multiple fronts south of Baghdad yesterday after battling Republican Guard troops protecting key routes to the Iraqi capital.

At the same time, about 40 satellite-guided bombs continued to pound a "heavily secured" storage facility in Baghdad used by forces loyal to Iraqi leader Saddam Hussein, said the US Central Command.

Dagger o­n the heart

Meanwhile the battle to take control of various other cities is also proceeding well with US troops gaining upper hands in the gunfights with forces loyal to Iraqi president Saddam Hussein.

According to Reuters , The US armored forces, backed by fearsome air power, moved beyond the towns of Kerbala and Kut, capturing key bridges over the Euphrates and Tigris rivers, making the distance to Baghdad much closer.

"The dagger is clearly pointed at the heart of the Baghdad regime," US Brig Gen Vincent Brooks was quoted by Reuters as saying, adding that the vanguard of the 3rd Infantry and the Marines moved to within 32 kilometers of Baghdad.

The news agency also added that during the night US spy planes spotted Iraqi Republican Guard units moving south from the capital to counter the US attack and reinforce positions around the airport.

Brooks was also quoted by the Washington Post as saying that the continuing US bombing campaign against Republican Guard units in recent days resulted in these Iraqi forces moving to terrain they prefer to defend.

No operational pause

He said the pounding of the Republican Guards is proof that US forces had not undertaken an "operational pause", as was reported during the last week by some US officers in the field.

"While some believed there was a pause, the Republican Guard recognizes there was no pause," Brooks added, and summed up the condition of these Iraqi divisions as : "First, they're in trouble. Two, they're under serious attack right now and those attacks will continue until we're finished with the task at hand. The attacks will continue over the next few days."

The Post also quoted Brooks as saying that with each passing day, advancing US troops are getting more help from Iraqi civilians who recognize that the regime of Saddam Hussein will no longer be in power.

Complete illusion

Meanwhile, in Baghdad, Iraqi Information Minister Mohammed Saeed al-Sahaf denied reports that coalition forces had crossed the Tigris River and were approaching Baghdad, saying they have lost significant numbers of troops and equipment.

"They are lying every day, they are lying always and mainly they are lying to their public opinion," CNN quoted Sahaf as saying. "What they say about a breakthrough is completely an illusion." He also said that the coalition forces were bombing historic and religious sites.

Iraqi television also carried comments by the commander of the Baghdad division - which the US says it destroyed - saying o­nly 17 of his men had been killed and 35 wounded.

The Post also reported of the damage in Baghdad due to the continuing bombing by the invading forces.

"The bombing of the capital's telephone exchanges in recent days has left the city's 5 million residents in near isolation. At least six exchanges have so far been hit, some more than o­nce, and most of the city's lines are now down," said the Post .

Maternity hospital hit

The daily added that other targets in and around the capital were bombed throughout the day, as more and more of the capital's military installations and communications infrastructure is dismantled. Buses were running, but street traffic was much less than normal.

It quoted reporters as saying that air strikes hit a maternity hospital operated by the Red Crescent, the Muslim equivalent of the Red Cross, causing heavy casualties and extensive damage.

Reuters

reported that the maternity hospital was struck as US planes fired missiles into a neighborhood called Mansour, hitting Baghdad's international trade center and two labor union buildings. The news agency quoted witnesses saying several people in the hospital were killed, along with motorists whose cars were struck as they drove through the area.

Brooks said he had no information about the reported strike o­n the hospital.

In other developments, Arabic broadcaster Al-Jazeera says it will suspend the work of its correspondents in Iraq indefinitely after the Information Ministry banned two of them from working

And the Iraqi television showed footage of Saddam smiling and laughing with members of his cabinet; although BBC said it was not clear when the pictures were taken.