Sept 20 (Reuters) - United Airlines removed 25 of its Boeing 777-200 airplanes from service this week after discovering it failed to perform required inspections on the wing leading-edge panels, a U.S. regulator said.

The Federal Aviation Administration (FAA) said the airline disclosed the issue to the agency and proposed a plan to complete the inspections. United said Tuesday it canceled some flights Monday night and Tuesday morning to conduct inspections but does not expect to cancel additional flights because of the issue. (Reporting by David Shepardson Editing by Chris Reese)