But officials would not confirm or deny Iraqi reports of civilian casualties.

``We make every effort to avoid civilian casualties but Iraq must realise that we will strike back to enforce the no-fly zones and to protect our airmen,'' a Pentagon official said.

``The best way for Iraq to avoid casualties is to stop provoking the attacks,'' said the official, who spoke on condition of anonymity.

Iraq said 17 civilians were killed and 18 others wounded in the air attacks yesterday in the Najaf region, in what would be one of the deadliest attacks since Operation Desert Fox, the four days of air strikes launched by the United States and Britain in December.

The victims were mostly women, children and elderly people, the official Iraqi News Agency (INA) said.

``The US administration and its ally, Britain, committed anew crime by carrying out an attack in the Najaf region,'' INA said.

Homes were also destroyed, INA said, in the region which centres around the Shiite Muslim holy city of Najaf, housing the tomb of Ali, a key Shiite religious figure.

In a statement, the US Central Command said US Air Force F-16 fighting Falcons and US Navy F/A-18 Hornets and F-14 Tomcats yesterday struck an Iraqi SAM site 320 km from Baghdad near Abu Sukhayr, and a military communications site 240 km southeast of Baghdad near Al Khidr.

The Command said the strikes were in response to Iraqi anti-aircraft artillery fire at coalition aircraft patrolling a no-fly zone over southern Iraq.

``There were no coalition aircraft damaged during the incident and battle damage assessment is ongoing,'' the statement said.