The Project Wedgetail Boeing 737s taking shape in a highly secured hangar at the Amberley Air Force base west of Brisbane, Australia, are blandly described as Airborne Early Warning and Control (AWEC) aircraft.

In truth they will become the gate keepers of the slaughter ground that the Australian Defence Force will create in whatever part of the continent is invaded in future hostilities.

Close up these 737s bristle with metal blisters, barbs, and small bubble-shaped devices of uncertain intent, as well as fish-like under fins and the more normal looking radar array on top.

Not so much another example of the world's most commonly flown jet airliner, but a warthog with wings, or something out of a sci-fantasy comic.

But there are a few problems for this extraordinary and mostly top secret US$3 billion ($4.4 billion) programme, as defence industry media were candidly told on being taken into this strangest of assembly lines for 737s for a first public showing.

The Northrop Grumman Multi-role electronically scanned array (Mesa) radar system isn't working as intended, or with the other systems it must integrate with in battle.

The Wedgetails, due for delivery last November, and then delayed until late next year, have just been delayed a further six months for initial deliveries in March 2009.

And while the Australian investment is half a billion for each jet, Boeing has taken the additional development costs into its accounts, with a fresh charge of US$274 million on top of an earlier US$496 million write-off.

The six jets involved come off the airliners' civilian assembly line in Seattle as empty aircraft, are flown to Amberley, pulled apart and securely reassembled with classified systems and weapons.

Airlines get civil 737s for as little as US$25 million each if ordered in bulk, although the list price is much higher.

But as the officials who showed off the partially re-assembled Wedgetails explained, these are not even ordinary early warning jets, never mind airliners.

"The Mesa radar brings 360 degree continuous coverage. This is world beating in its class," says Air Vice-Marshal Chris Deeble.

When it works it will be, and the potential market is huge.

South Korea has also ordered Wedgetails, which were proposed by Boeing as the answer to an Australian need to find and kill everything from enemy warships down to single commando infiltrators in the event of an attack on isolated but strategically vital communities, and the country's mineral and petroleum assets.

The new vice president for Boeing's AWEC project, Maureen Dougherty, who was sent to Australia from running nuclear missile programmes to knock the Wedgetails back into form, says "We would of course like to see this platform ordered by the United States".