The US Army's nightmare in Iraq continued on Friday when one of its Black Hawk helicopters, with six soldiers on board, crashed near deposed president Saddam Hussein's hometown of Tikrit.

"We can confirm all six on board are dead," said army spokesperson Major Josslyn Aberle.

Another Black Hawk that was flying with it did not notice any hostile fire, Aberle said.

But local Iraqis blamed the crash on ground fire, CNN quoted a senior US military official as saying.

The Black Hawks were en route to Camp Ironhorse, the main US military base in Tikrit.

The crash came a day after a memorial service for 15 US troops killed when a CH-47 Chinook helicopter went down Sunday in Fallujah.

In further violence Friday, assailants ambushed a US military convoy in Mosul, killing one soldier and wounding six, according to the Coalition Press Information Centre and 101st Airborne Division.