LONDON – Boeing’s 787 Dreamliner is overweight and experiencing delays with some suppliers, the company said Sunday, while stressing that the long-range, fuel-efficient jet remains on budget and on schedule.

Rival Airbus, however, announced this weekend that the widely expected redesign of its planned A350 – billed as a competitor to the 787 – will nearly double the development cost of the plane.

Boeing Commercial Airplanes Chief Executive Alan Mulally, speaking in London on the eve of the Farnborough Air Show, declined to say where 787 supply problems were occurring or by how much the plane was exceeding its target weight.

“We’re a little over where we want to be at this time on weight, but ahead of where we were on previous programs, so we’re really focused on weight-efficient structure right now,” he said.

Mulally emphasized that the plane remains on course for its first flight in mid-2007 and entry into service the following year.

“Some partners are a little behind on the schedule but we’re working with them on recovery plans,” he said, adding that “the systems are coming together really well, the electrical power looks good” and the plane’s Rolls-Royce PLC and General Electric Co. engines come “very, very close to their performance goals.”

Boeing Co. does not disclose development costs for its aircraft, reported to be about $9 billion.

Company spokesman Charlie Miller said the supply and weight issues alluded to by Mulally would not affect the program’s budget.

“At the moment there’s nothing that’s actually going to increase costs or delay the schedule,” Miller said.

With 360 firm orders in the bag two years before the first delivery, Boeing claims the Dreamliner program has already earned the title of most successful jet launch.

The plane’s popularity has contributed to the woes at European rival Airbus, which has so far won just 100 orders for its planned A350.

Tom Enders, the co-CEO of Airbus parent European Aeronautic Defence and Space Co., confirmed Saturday that the company will announce a long-expected revamp of the A350 at Farnborough, which starts today. The revamp will increase the A350’s development cost to about $10 billion from the previously estimated $5.7 billion. Details are to be announced today.

Airbus is seeking to reassure customers and investors at Farnborough – one of the biggest events in the aeronautical industry with some 1,500 exhibitors from 35 countries – that it is on the road to recovery.

Last month’s announcement of a further seven-month delay for the A380 superjumbo sent EADS shares plunging and led to the departure of Airbus CEO Gustav Humbert and EADS co-CEO Noel Forgeard.

The 555-seat A380 will take part in the daily flying displays at Farnborough, where 300,000 visitors are expected this year, but Airbus executives are likely to face a tougher crowd indoors.

Airbus reported this week that its sales fell by more than half in the first six months of the year to 117 planes, compared to Boeing’s 480 orders for the same period.

Outside the Boeing-Airbus competition, Brazilian plane maker Empresa Brasileira de Aeronautica SA – better known as Embraer – is scheduled to showcase its 190 airliner, one of its largest models at 180 seats.