GENEVA (AFP) -- The United States on Tuesday pledged to take further moves to reach a negotiated settlement with the European Union in a dispute over government assistance to the civil aviation sector.

"We've made clear that we remain open to a negotiated settlement," Deputy U.S. Trade Representative John Veroneau told a press conference at WTO headquarters here.

"If you can reach a settlement that secures your interests, obviously a settlement is always the preferred option. "So I reiterated our interest in doing that and we're glad to explore that further."

The United States and the European Union lodged complaints against one another at the World Trade Organization in November 2004 challenging EU subsidies to European aircraft manufacturer Airbus and U.S. government assistance to rival Boeing.

"Airbus is going through a lot of changes right now and we are respectful of the measures that they are considering internally, and if the situation avails itself for us to explore a possible way forward to negotiate something, then we're open to do that," Veroneau said.

Airbus, plagued by damaging delays to its A380 superjumbo program, has undergone top management changes and is to be overhauled under a recovery plan dubbed Power 8.

Airbus A380 certified air worthy

The Airbus A380, the world's largest civilian airliner, received its air worthiness certificate from U.S. and European authorities Tuesday, 10 months before Singapore Airlines is to get the first commercial model.

The certificate was signed by Patrick Goudou for the European Aviation Safety Agency and John Hickey for the U.S. Federal Aviation Administration at an Airbus facility in Toulouse, southern France.

Standing in a hanger before a massive A380, Louis Gallois, chief executive of Airbus and co-chief executive of the parent group EADS said: "This double seal of approval represents a key milestone for the A380 program.

"It recognizes the quality of the work performed by all those who have worked hard for many years" to develop the superjumbo jet.

Gallois, who was named head of Airbus in October to resolve chronic production problems with the A380, said the certification "confirms that the aircraft is meeting or exceeding the expectations in terms of performance, range and environmental friendliness and cabin comfort.

"Both customers and their passengers will love it," he vowed.

Five A380 test aircraft have carried out more than 800 flights lasting 2,600 hours in a test campaign that began in April 2005.

Singapore Airlines was to have received its first A380 early this year but delays have progressively pushed back the plane's arrival.

Airbus has said SIA'S first A380 -- one of 19 ordered by the carrier -- will now be delivered in October 2007.