WASHINGTON, May 17 (Reuters) - NASA and Boeing ( BA )

delayed the launch of Boeing's ( BA ) Starliner crew capsule again on

Friday, giving them four more days to assess a helium leak

before attempting to launch the spacecraft's first two

astronauts into space, the space agency said Friday.

Starliner's liftoff from Florida has been delayed several

times in May and it was last scheduled for May 21.

Aside from the helium leak, a technical issue with its

Atlas 5 rocket had prompted an earlier delay. The program is

several years behind schedule and more than $1.5 billion over

budget.

The latest postponement will give more time "to finalize

next steps that address a stable helium leak", NASA said. The

launch is now targeted for no earlier than 3:09 p.m. EDT (1909

GMT) on Saturday, May 25.

Boeing ( BA ) has been developing Starliner for more than a

decade to provide NASA with a second U.S. spacecraft capable of

ferrying astronauts to and from the International Space Station.

SpaceX's Crew Dragon capsule, built under the same NASA program,

first launched astronauts to space in 2020.

Starliner's latest mission, called the Crewed Flight

Test, is due to be the final test before the spacecraft is

certified by the U.S. space agency to fly routine astronaut

missions to the ISS. Boeing ( BA ) completed an uncrewed Starliner trip

to the ISS in 2022 following years of technical and management

issues.