TOKYO (Reuters) -- Nissan Motor Co. is preparing a diesel-powered version of its Titan full-sized pickup truck by 2009 for the United States, with engines built by U.S. truck and engine maker Navistar International Corp., industrial daily Nikkan Kogyo Shimbun reported today.

Automotive News reported in May that Nissan North America was studying plans to sell Titans with V-8 diesel engines and V-6 gasoline engines in an effort to broaden the truck's appeal.

The company wants to improve its marginal position in the fierce North American full-sized pickup market.

International Truck and Engine Corp., Navistar's principal operating company and the exclusive supplier of diesel engines to Ford Motor Co.'s Super Duty pickups, will supply Nissan with the V-8 diesel engines, the Nikkan Kogyo said.

The Titan is now powered by a 5.6-liter V8 gasoline engine.

Nissan is due to launch a diesel version of its Maxima sedan in the United States in 2010 with engines produced by Renault SA, which owns 44 percent of Nissan.

Japan's third-biggest automaker, Nissan offers no diesel vehicle now in the United States, where the fuel-efficient powertrain is used mostly on commercial vehicles including large pickup trucks.

A spokeswoman at Nissan said the company could not comment on future product plans.

Nissan launched the Titan, its first and only full-sized pickup, in 2004 hoping to carve a place in the lucrative, U.S.-dominated segment, but sales have failed to live up to expectations.

In May, Nissan sold 4,899 Titans, down 18 percent from the year before. So far this year, sales are down 15 percent at 28,668 units.

A 2008 model year Titan went on sale in April in a segment facing stiffer competition from Toyota Motor Corp.'s remodeled Tundra. Toyota has hinted that it would eventually offer a gasoline-electric hybrid version of the Tundra.

The U.S. pickup market is dominated by Ford's F-Series and General Motors' Chevy Silverado, the two best-selling vehicles in the world's biggest auto market.