WASHINGTON  - The National Transportation Safety Board said on Wednesday a partial government shutdown would force the agency to suspend its investigation into the cabin panel blowout on a Boeing 737 MAX 9.

Congress faces a Friday night deadline to continue to fund some government operations.

NTSB Chair Jennifer Homendy said in a letter that because the MAX 9 planes remain grounded by the Federal Aviation Administration "there is no known imminent threat to the safety of human life or protection of property that would justify the continuation of ongoing work" if there is a partial government shutdown.

"Many investigations with national safety relevance may not be undertaken or completed and any resulting safety recommendations potentially foregone," Homendy wrote.

"Other critical work such as assistance to families of victims, safety studies, or advocacy efforts would be delayed or canceled depending on the timing and length of a lapse."

Homendy told reporters after a Senate Commerce briefing on the MAX 9 that the agency could send investigators if new incidents arose but said it could not continue the MAX 9 investigation in the event of a partial government shutdown.

The NTSB would be forced to stop all investigations in the same stage, she added.

Homendy also said a full year temporary funding bill would force NTSB to freeze hiring and reduce current staffing levels and halt modernizing IT systems.

(Reporting by David Shepardson; Editing by Kirsten Donovan)