LOS ANGELES -- US space firm SpaceX has pushed back its first launch of a US military satellite after a "sensor issue" with the rocket triggered a 24-hour delay on Sunday.

"Standing down today due to a sensor issue; backup launch opportunity tomorrow morning," the California-based company tweeted.

A Falcon 9 rocket was less than 60 seconds away from liftoff on Sunday when the issue triggered a hold.

Liftoff, which is now targeted on Monday between 7 and 9 a.m. EDT (1100 and 1300 GMT) from the Kennedy Space Center in Florida.

Following stage separation, the first-stage booster will attempt to land at SpaceX' s Landing Zone 1 (LZ-1) at Cape Canaveral Air Force Station, Florida.

The mission, which is being referred to as NROL-76, will carry a classified payload designed, built and operated by the National Reconnaissance Office.