A U.S. fighter plane and a Black Hawk helicopter have gone down in central Iraq. The incidents occurred as American troops advanced to within 20 kilometers of Baghdad.

The F/A-18C jet fighter from the U.S. carrier Kitty Hawk reportedly was shot down Wednesday afternoon. Coalition officials would not comment on the fate of its lone pilot but said notification of family was in process.

VOA correspondent Alisha Ryu was on a patrol with a unit searching for the pilot around a lake near Karbala, in central Iraq, about 100 kilometers south of Baghdad.

"There's quite a few tanks and Bradley fighting vehicles and Hum-Vees, and they're searching the area where they believe that they can see the fin tail of the plane sticking out of the water, and it did make impact with the water," she said. " So they're doing foot patrols, as well as looking out with binoculars, and trying to assess where they might come down. They're looking for footprints of possibly the pilot coming out, if he had made it, if he had ejected. They're looking for any signs that he has come out of that airplane alive. So far, nothing at the moment."

Coalition forces also announced that a Black Hawk helicopter crashed near Karbala while on an operational mission. At least a half dozen soldiers were on board. Coalition officials provided no further details, saying an investigation was under way.

The crashes come as U.S. troops clashed with forces of Iraq's elite Republican Guard near Karbala and the city of Kut, also about 100 kilometers south of Baghdad. The deputy coalition operations manager, Brigadier General Vincent Brooks, told reporters the U.S. troops inflicted heavy losses on at least one division of the Republican Guard.

"The 1st Marine Expeditionary Force attacked the Baghdad Division near al-Kut and has crossed the Tigris River. The Baghdad Division has been destroyed," he said.

Some U.S. troops were reported to have advanced to positions 30 kilometers from the Iraqi capital. They were well inside what coalition officials call the red line, an imaginary ring around Baghdad inside which they say Iraqi forces might use chemical or biological weapons.

Iraq's information minister, Mohammed Al-Sahhaf, however, denied the coalition claims in a broadcast on Iraqi television.

"They are lying always," he accused, " and mainly they are lying to their public opinion. Therefore what they have alleged about a breakthrough, this is completely an illusion."

President Saddam Hussein was seen on Iraqi television meeting with his top military advisers, but there were no indications of when the meeting actually occurred.

Iraqi state television Wednesday called on Iraqis to turn in their mobile phones, saying it believes some people are using them to collaborate with the enemy.

The U.S. Defense Department has said its military commanders for weeks have been in contact with senior Iraqi commanders by mobile phone and internet e-mail.

Finally, coalition spokesmen Thursday announced that Private Jessica Lynch had been flown to a U.S. base in Germany for medical treatment. Private Lynch was rescued by special operations forces Tuesday night from an Iraqi hospital near Nasiriyah. She was captured and wounded in an ambush one week ago.