WASHINGTON, Sept 2 (Reuters) - The Federal Aviation Administration (FAA) on Thursday barred Virgin Galactic from flying its SpaceShipTwo until the agency approves its final mishap investigation report from its July flight or determines the issues do not affect public safety. The FAA confirmed on Wednesday that it was investigating a deviation in the descent of the flight of the Virgin Galactic rocket plane that carried British billionaire Richard Branson to the edge of space on July 11. The FAA, which is responsible for protecting the public during commercial space transportation launch and reentry, said "SpaceShipTwo deviated from its Air Traffic Control clearance as it returned to Spaceport America" in New Mexico. "Virgin Galactic may not return the SpaceShipTwo vehicle to flight until the FAA approves the final mishap investigation report or determines the issues related to the mishap do not affect public safety," the agency said. Virgin Galactic did not immediately respond to a request for comment. On Wednesday it acknowledged that "the flight"s ultimate trajectory deviated from our initial plan" but added it "did not fly outside of the lateral confines of the protected airspace." Virgin Galactic said "the flight did drop below the altitude of the airspace ... for a short distance and time (1 minute and 41 seconds)." Virgin Galactic separately on Wednesday said it was planning another SpaceShipTwo flight from New Mexico and targeting a flight window in late September or early October, pending technical checks and weather. That flight is to carry three crew from the Italian Air Force and National Research Council, it added. Branson, one of six Virgin Galactic employees who took part in the July flight, soaring more than 50 miles (80 km) above the New Mexico desert, had touted the mission as a precursor to a new era of space tourism and said the company he founded in 2004 was poised to begin commercial operations next year.