The Senate transportation committee is launching a probe looking into whistleblower complaints accusing the Federal Aviation Administration of improperly training its safety inspectors to review the Boeing 737 Max jets.

"In light of recent 737 crashes in Indonesia and Ethiopia, the committee is investigating any potential connection between inadequate training and certification of Aviation Safety Inspectors who may have participated in the FSB evaluation of the 737 MAX," Sen. Roger Wicker, chairman of the committee, wrote to FAA Acting Administrator Daniel Elwell on Tuesday.

"Allegations from these whistleblowers include information that numerous FAA employees ... had not received proper training and valid certifications."

Wicker said the FAA may have been notified about these deficiencies as early as Aug. 2018 and that an FAA investigation into the allegations may have already been completed.

In response to CNBC request for comment, the FAA cited Elwell's statement at a Senate Commerce Committee hearing last week: "In our quest for continuous safety improvement, the FAA welcomes external review of our systems, processes, and recommendations," he said.

Boeing's 737 Max jets have been grounded for over two weeks. The company is currently working on a software fix for the plane's flight-control systems after two crashes of Max jets in Indonesia and Ethiopia killed 346 people.