WASHINGTON, Jan 12 - The head of the Federal Aviation Administration told Reuters Friday the agency plans "closer monitoring" of the 737 MAX 9 after the plane returns to service following a mid-air cabin blowout.

FAA Administrator Mike Whitaker said it is "pretty clear" the Alaska Airlines 737 MAX 9 cabin blowout was a manufacturing issue, not a design problem, and vowed a comprehensive audit of Boeing production issues.

"This has been going on for a while and whatever's happening isn't fixing the problem," Whitaker told Reuters, adding he would not approve the MAX 9 return to flights until the agency is convinced "there's no chance of this happening again." (Reporting by David Shepardson; Editing by Chizu Nomiyama)