A new round of competition between two airplane giants heated up Wednesday as airplane producer Boeing said its selling focus over the next 20 years will be twin-aisle planes, posing a challenge to its rivals in China, the world's second largest aviation market after the US.

Boeing will sell about 700 twin-aisle airplanes to China in the next two decades, focusing on planes with between 250 and 350 seats, which mainly fall in the 787 and 777 families, Marc Allen, head of Boeing China, said in Beijing.

"Our targeted selling plane is the size less than the jumbo, but bigger than the single-aisle airplanes," Allen said, noting that Boeing will deliver 120 single-aisle 737s to China this year. He  believes Boeing will deliver 60 percent more airplanes this year than last year in China.

Allen made the remark on the heels of Boeing's 787 Dreamliner resuming delivery after a four-month halt due to battery problems.

James P. Mueller, vice-president of Atlantic and Pacific Sales with United Airlines Inc, Wednesday said at a briefing in Beijing that United has confidence in the returning of 787, and trusts it is reliable. UA will restart its 787s flying Monday.

As for the Chinese market, Boeing will deliver 787s to two Chinese airlines, Hainan Airlines and China Southern Airlines, before the end of the second quarter of this year, Allen said.

However, Allen said the real competition in twin-aisle airplanes is the A350 from Airbus, as the model also features a wide body and long-distance flying capabilities.

On Tuesday, the first A350XWB finished being painted in Toulouse, France, and it will make its maiden flight this summer.

Last month, Airbus CEO Fabrice Brégier said in Beijing that he believes the A350 family will be more attractive than the 787 family as the plane is bigger, which will attract more customers.

So far, Airbus has won 616 orders for the A350 family from 35 clients worldwide.