European plane maker Airbus said it has resolved the snags that forced it to delay deliveries of its 555-seat A380 superjumbo by up to six months.

It has been forced to hire more engineers after finding that the amount of work needed to adapt to demand for customized cabins had been underestimated. It also had to redesign part of the wiring that girdles the plane in order to ensure all the modifications required by airlines would work.

"There is no technical showstopper, just bottlenecks in engineering and electrical harnesses" said Charles Champion, who heads the A380 program.

While engineers came up with a solution, Airbus disclosed that deliveries of plane parts from across Europe to the final assembly plant in Toulouse were frozen for three months up to mid-August.

But it said the changes to Europe's most ambitious industrial project had been completed without adding to the EUR1.45 billion (USD$1.77 billion) of cost overruns that had already been budgeted when the plane was considered overweight at the end of last year.

Those overruns do not include penalties owed to airlines for the late deliveries, however.

Airbus new Chief Executive Gustav Humbert told French reporters last week the cost of these would be less than EUR100 million but rowed back on Thursday, saying the final figure needed to be negotiated.

Since starting test flights earlier this year, the A380 has flown over 300 hours, occasionally touching speeds close to the sound barrier, or Mach 0.95, when thrown into a test dive, Champion said. The maximum operating speed will be 0.89 Mach.

"We have really tortured the plane," Champion told journalists.

The first plane due to be delivered commercially is one of five A380s taking shape under an undercoat of green paint in the assembly plant, with only the livery on the tail giving away its future owner -- Singapore Airlines, which will receive the plane in November or December 2006.

So far one plane a month is coming through the assembly chain but this is scheduled to increase to just over four a month and Champion said Airbus was looking at whether to increase this even further to catch up with lost output. No decision had been taken.