SpaceX said it was standing down on Wednesday's launch of the U.S. military's X-37B robot spaceplane on its seventh mission to orbit.

"We are standing down from tomorrow's Falcon Heavy launch of USSF-52 to perform additional system checkouts," SpaceX said in a tweet on Tuesday, without confirming a new launch date.

The original plan to send the spacecraft to orbit late on Sunday was scrubbed due to poor weather conditions at the Cape. (Reporting by Baranjot Kaur in Bengaluru; Editing by Christopher Cushing)