Boeing has revealed plans to build a larger version of its 747 aircraft as it tries to win business before the launch of the rival Airbus A380.
The Boeing 747 has been flying for more than 30 years
The new 747-8 Intercontinental will be Boeing's largest ever jetliner, with 450 seats compared to 416 now.
Boeing has $5bn (£2.8bn) in orders for freight versions of the 747 but has yet to agree any passenger jet deals.
Boeing hopes the plane will help it compete better against the A380,which can carry up to 800 people.
The Airbus 'superjumbo' plane is due to enter service next year.
The US company said the 747-8 - nearly 12 feet longer than the current 747 - would cost 20% less to operate per flight than the A380.
Analysts said the new plane would extend the lifespan of the 747, which has been in service for 35 years.
Boeing is currently developing a mid-sized aircraft - the 787 - for launch in 2008 and will incorporate technology designed for it into the 747-8.
This will make the new plane quieter and more fuel efficient.
Boeing is currently in discussions with a number of airlines about ordering the new 747.
The Airbus A380 is due to go into service next year
Delivery dates will depend on the needs of individual customers, it said.
"There is a lot of interest out there in the passenger version," a Boeing spokesman told the BBC.
Boeing believes there will be demand for 900 new passenger and freight planes with a capacity of more than 400 seats in the next 20 years.
Analysts said an increase in the 747's capacity would put pressure on Airbus, which has staked its future on the success of the A380.
Airbus has secured 159 orders for the A380 but production is running about four months behind schedule.
The delays mean the first A380 will not be delivered until late 2006, forcing Airbus to compensate airlines which have ordered the plane.
Richard Aboulafia, from aerospace analysts Teal Group, said the larger 747 would help "box the A380 into an even smaller niche".
Luxembourg cargo firm Cargolux Airlines and Nippon Cargo of Japan have ordered a total of eighteen 747-8 freight planes.
These will be delivered in 2009.