Over the past six months, the Transportation Security Administration ramped up civil citations to passengers, mostly aboard airplanes, who refused to comply with mask mandates, slapping them with more than $640,000 in proposed fines, according to a government report released on Monday.

It was a stark increase compared with a six-month period from February to Sepember of last year, when the T.S.A. issued more than 2,000 warnings and fined just 10 passengers a total of $2,350, according to a news release in October.

In total, between Feb. 2, 2021, and March 7, 2022, the agency fined 922 people for violating mask mandates and issued 2,709 warnings, the report, by the Government Accountability Office, said.

The wearing of masks to stop the spread of the coronavirus became a cultural flash point during the early months of the pandemic and has continued to be polarizing.

Last week the Biden administration extended the mask mandate for air travel and public transportation to April 18, while the Centers for Disease Control and Prevention reviews the policy to see if it is still necessary.

Both the T.S.A. and the Federal Aviation Administration investigate incidents in which people do not comply with mask mandates. The T.S.A.’s authority is not limited to air travel, but covers airports and other modes of public transportation. During 2021, the F.A.A. proposed more than $5 million in fines for unruly airplane passengers; most of the incidents were mask related.

R. Carter Langston, a spokesman for the T.S.A., said the process for reporting incidents became better understood in the past six months, which is why the citations and penalties increased so significantly.

In late October, the chairman of the House Homeland Security Committee, Representative Bennie Thompson, Democrat of Mississippi, urged the T.S.A. to enforce more penalties.

The report did not include any recommendations for the agency.