By Andrea Shalal

ABOARD THE USS WASP (Reuters) - Nearly two weeks of testing of Lockheed Martin Corp's F-35B fighter jet on an amphibious assault carrier proved the stealthy new warplane can operate and be serviced at sea, U.S. and UK officials said this week, marking another step toward the jet's readiness for initial combat use by the Marine Corps.

Six F-35 B-model jets, which can take off from shorter runways and land like a helicopter, completed 98 separate flights, logging 73.1 flight hours, on the USS Wasp from May 18 to May 26, said Marine Corps spokesman Major Paul Greenberg.

The jets were due to wrap up a final day of flight tests on Wednesday from the ship, which is operating about 100 miles off the coast of North Carolina, officials said. Maintainers working on the jets will wrap up their work on Friday, they said.

Lieutenant General Jon Davis, the top Marine in charge of aviation, told reporters on the ship that the testing showed “the airplane is right at home at sea." The reporters were ferried to and from the Wasp on Tuesday while it was conducting tests at sea.

Davis said the new jets would expand the U.S. military's ability to respond to crises, since it will allow Marines for the first time to fly stealthy jets off warships.

Davis, who will attend meetings in Norway this week with the major companies and countries involved in the $391 billion weapons program, said the Marines remained on track to declare an initial squadron of 10 jets ready for combat use in July.

He said work was still under way to retrofit those initial jets, and some changes in ship maintenance procedures would be made after the operational testing, but "no showstoppers" had emerged to derail the planned declaration around July 15.

One F-35B jet had to fly back to shore after a landing gear warning signal came on after takeoff, but it was replaced by another jet standing by at a North Carolina Marine Corps base, officials said. They called the incident minor.

Major Mike Rountree, a Marine Corps pilot, said the jet was easier to fly than the AV-8B Harrier, and he was "a lot less terrified" to carry out a night landing in the F-35B.

(Reporting by Andrea Shalal; Editing by Phil Berlowitz)