Airbus revealed new delays for its troubled A380 superjumbo jet on Thursday, blaming a repeat of wiring installation problems which have already pushed the program a year behind schedule and hit future profits.

Bowing to pressure to either confirm or deny reports of another logjam in the twice-delayed airliner project, Airbus parent EADS said it was too early to say how long the latest delivery delay would last or how much it would cost.

Shares in EADS fell by as much as 3.9 percent, slicing 750 million euros off the value of Europe's top aerospace group. At mid-session in Paris they were down 2.3 percent at 22.3 euros.

The 12-billion-euro ($15 billion) program to produce a new class of mammoth plane has already been hit twice by problems in fitting each jet's 500 km (300 miles) of wiring, culminating in a 2 billion euro profit warning and management shake-up in June.

Although the company's assessment is still under way, continuing industrialization challenges with the wiring of production aircraft have been identified and are being tackled, EADS said in a statement.

Consequently, from what is known today, there will be further delays.

Airbus Chief Executive Christian Streiff, who was appointed in July to sort out the crisis, had ordered a full report on the project by end-September. But on Thursday EADS said Airbus needed up to four weeks from now to complete the internal audit.

Streiff has already replaced the head of the A380 program.

The delays are the latest blow to Europe's flagship project to build a double-decker airliner capable of carrying 555 people in three classes or more than 800 in all-economy seating.

Airbus faces penalties to airlines which signed up to buy the $300 million passenger jet, the largest ever built.

It is under pressure to deliver as arch-rival Boeing woos airlines with an alternative strategy of buying smaller jets such as its fuel-efficient 787 or switching to the latest stretched version of its veteran jumbo, the 450-seat 747-8.

The fact that they are a month late with the audit is the worst news we got today, said a London-based aerospace analyst who declined to be identified.

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Airbus laid on glitzy celebrations of the A380's official inauguration and maiden flight last year, but the design team's euphoria faded when the aircraft moved into mass production.

Assembly workers in Toulouse, southern France, have been bogged down for a year in airlines' request for special cabin features and frills that affect each plane's wiring layout.

To save face, analysts expect the first A380 to be delivered to Singapore Airlines on time by end-December. But doubts have been growing over the schedule for 2007 and beyond.

The extra delay also comes as Airbus is reeling from a decision by British partner BAE Systems to sell its 20 percent stake back to EADS along with a public warning that the A380 program is set to soak up more management time and cash.

BAE Systems CEO Mike Turner said last week he expected further delays in the A380 program and said one of the reasons the firm was ending decades of UK investment in Airbus was its concern that the planemaker would need more development money.

EADS has meanwhile been rocked by a Russian decision to buy a 5 percent stake in the French-German-Spanish group, taking advantage of cheap share prices caused by the A380 setbacks.

The share swoop and a Kremlin aide's suggestion of further Russian purchases have alarmed EADS management and are likely to be raised at a summit of French, German and Russian leaders outside Paris on Saturday.

French Finance Minister Thierry Breton expressed support for the new EADS and Airbus management on Thursday.

I don't see any dysfunction at the moment. I have confidence in EADS and Airbus, he told i-Tele television.

EADS shares have fallen 30 percent so far this year as the French, German and Spanish company grapples with the A380 crisis and a costly redesign of its long-range A350 twin-jet, which it desperately needs to compete with Boeing's successful 787.

Over the same period EADS has underperformed Boeing by 36 percent before currency adjustments as Boeing's shares rose.

(Additional reporting by Jason Neely)