U.S troops entered a major city south of Baghdad Tuesday as coalition warplanes blasted new targets in and around the Iraqi capital, including elements of the Republican Guard. Meanwhile, Iraq's information minister read a message on state television he said was from Saddam Hussein calling for a holy war against U.S.-led forces.

American troops entered the strategic city of Najaf south of Baghdad Tuesday as they continue their push, albeit slowly, toward the Iraqi capital.

VOA correspondent Alisha Ryu says U.S. troops are now in the process of securing Najaf.

"The commander, his name is Colonel Ben Hodges, says that local people have been spotting Iraqi troops and police leaving the city all day long, and they were able to help some of the American soldiers come in and try to secure the town as best as they could," she said. In the air campaign, coalition warplanes pounded government targets in Baghdad and Republican Guard positions arrayed around the capital. Witnesses said the bombing attack was among the most intense of the war so far.

Iraqi Information Minister Mohammed al-Sahaf says 19 civilians were killed and more than 100 people wounded in the recent wave of bombings.

Later, Mr. al-Sahaf read a statement that he said was from Saddam Hussein calling on Iraqis to launch a holy war against coalition troops. The statement renewed questions about the whereabouts of the Iraqi leader who has been seen only briefly on state television since the war began.

In Washington, Defense Secretary Donald Rumsfeld denied what he said were rumors being spread by the Iraqi government that cease-fire negotiations were underway with Iraqi leaders:

"Since this broadcast is sent into Iraq, let me say this to all Iraqis who are listening: The regime is not telling the truth," he said. "There are no negotiations taking place with anyone in Saddam Hussein's regime. There will be no outcome to this war that leaves Saddam Hussein and his regime in power."

Also Tuesday, U.S. military officials both in Washington and at Central Command headquarters in Qatar expressed regret for an incident that led to the deaths of at least seven Iraqi civilians Monday and say it is now under investigation.

U.S. troops shot at a van loaded with civilians, including women and children, as it approached a military checkpoint near Najaf. U.S. officials say they fired warning shots but the van refused to stop.

U.S. troops are on heightened alert at the checkpoints following Saturday's suicide attack in which four Americans died.

"I'd like to express our regrets to the families of the Iraqis killed yesterday at the [U.S. military] checkpoint near Najaf," said the Chairman of the U.S. military Joint Chiefs of Staff, General Richard Myers, when he spoke to reporters at the Pentagon. "Loss of any innocent life is truly tragic."

General Myers also gave a spirited defense of the U.S. military strategy in Iraq. He was reacting to news reports that U.S. commanders underestimated the level of Iraqi resistance and could have used more troops and tanks before launching the ground war.

"It is not helpful to have those kinds of comments come out when we have troops in combat because, first of all, they are false, they are absolutely wrong, they bear no resemblance to the truth and it is just harmful to our troops that are out there fighting very bravely, very courageously," he said.

On the diplomatic front, U.S. Secretary of State Colin Powell is on a trip to Turkey aimed at smoothing relations with Ankara and other NATO allies that have been strained by the war in Iraq. Mr. Powell will also stop in Brussels and Belgrade.

Finally, Jordanian authorities say they have arrested several Iraqis suspected of plotting terror attacks on U.S. interests in Jordan. Jordanian officials believe the Iraqis were planning to poison water supplies intended for U.S. troops.