In anticipation of a longer war in Iraq, the United States on Friday said it has sent 130,000 more troops to boost its forces even as its senior ground commander admitted that the stiff Iraqi resistance is slowing the progress of the invading forces.

The 1st Armored Division in Germany, the 1st Cavalry Division in Texas, and the 2nd and 3rd Armored Cavalry Regiments in Louisiana and Colorado are among the units being deployed, the official said.

The US Army Senior Ground Commander in Iraq, General William Wallace, said 'tougher-than-expected' Iraqi forces have stalled the US drive towards Baghdad.

Long supply lines and Iraqi guerrilla-style tactics have reduced the chances the swift military planners had hoped for, he said.

"The enemy we're fighting is different from the one we'd war-gamed against," Wallace told The Washington Post at the Forward Operating Base Shell in Iraq.

A Pentagon official said in Washington that two huge 'bunker buster' bombs blasted Iraq's communication centre in Baghdad and fighting raged in strategic towns in the south.

PTI