WASHINGTON (Reuters) - Boeing Co and Sikorsky Aircraft, a unit of United Technologies Corp, said they were teaming up to develop a next-generation multi-role helicopter for the U.S. military.

The strategic teaming agreement, signed January 13 and announced on Friday, reunites two of the biggest U.S. helicopter manufacturers, who often compete for orders but joined forces to build the Comanche, a U.S. Army helicopter program that was canceled in 2004.

Sikorsky, maker of the Black Hawk utility helicopter, and Boeing, which builds Apache attack helicopters, plan to submit a joint proposal in response to an Army technology demonstration project unveiled earlier this month.

The Army program will lay the groundwork for the Pentagon's Future Vertical Lift program -- a massive project that will ultimately replace more than 4,000 medium-lift helicopters used by various U.S. military services.

Officials from Sikorsky and Boeing said joining forces on the competition would help the companies deliver an innovative, affordable helicopter.

"Our teaming agreement is the continuation of a long-standing relationship between Boeing and Sikorsky and reflects a common vision for the future of Army aviation," Chris Chadwick, president of Boeing Military Aircraft, said in a statement.

Mick Maurer, president of Sikorsky, said the agreement would "bring together innovative, industry-leading engineering expertise with a deep bench of program leadership talent." By pooling their resources, the companies will be able to offer the military "a revolutionary capability for the warfighter at an affordable cost for the U.S. taxpayer," he said.

The Army launched the technology demonstration project earlier this month, saying it would support the Pentagon's program to develop the next generation of vertical-lift aircraft with greater performance, reliability and affordability.

The two companies will compete with other industry teams to build and fly one or more demonstrator aircraft in 2017, which would then be evaluated for the bigger program.

(Reporting By Andrea Shalal-Esa; Editing by Gerald E. McCormick and John Wallace)