The U.S. Federal Aviation Administration (FAA) said it's conducting an investigation after a missing panel was discovered in a United Airlines Holding Inc. plane, Bloomberg news reported Saturday.

This report follows an announcement from the airline on Friday, stating that one of its Boeing 737-800 aircraft, carrying 139 passengers and six crew members, was found to have a missing external panel. The discovery was made after the aircraft safely landed at its scheduled destination, Rogue Valley International Medford Airport in Oregon, following its departure from San Francisco.

"We'll conduct a thorough examination of the plane and perform all the needed repairs before it returns to service," the airline said in a statement. According to FAA records, the plane was built in late 1998.

Boeing has faced heightened regulatory scrutiny since the January 5 Alaska Airlines incident, in which a door plug blew off mid-flight. This incident has prompted investigations into the company's safety and quality standards in its production process.

(With input from Reuters)