Republican Sen. Marco Rubio is accusing the Obama administration of "lying" to Congress about the security on U.S.-Cuba commercial flights -- saying officials have failed to follow through on a commitment to place federal air marshals on board those routes. 

In a letter to President Obama on Monday, the Florida senator noted that at a House Homeland Security Committee hearing last week, Transportation Security Administration official Huban Gowadia confirmed there are no air marshals on board commercial flights to Cuba. 

Yet at a May 17 Homeland Security subcommittee hearing, Department of Homeland Security official Seth Stodder said an air marshal agreement was being negotiated and flights would not begin without one.

“You and your administration’s lack of concern for the American people’s safety — as evidenced by allowing commercial, non-charter flights between the U.S. and Cuba to commence without the presence of federal air marshals, and lying about it to Congress — is further proof that you are putting your legacy ahead of the safety and security of the American people, including the people of Florida,” Rubio wrote.

Rubio, who is locked in a tough re-election race, said Gowadia’s revelation contradicts earlier claims by the administration that an agreement to include air marshals was finalized.

“Simply put, your administration has been caught in a bold-faced lie that has put American lives at risk,” Rubio said.

Rubio, along with New Jersey Democratic Sen. Robert Menendez, introduced legislation earlier this month -- the Cuban Airport Security Act -- that would stop flights to Cuba until a study was completed regarding the security measures at Cuba’s airports.

Commercial flights to Cuba began at the end of August, and Rubio called it “astonishing” that this was allowed to happen "under the false pretense that there would be federal air marshals on board."

“You have created an opportunity for our worst fears to become reality, just as they did on September 11, 2001,” he wrote.

Rubio asked Obama when he expects the Cuban government to sign the agreement on air marshals, what the TSA is doing to mitigate security risks, and if any White House official instructed the TSA to allow flights before “appropriate security procedures” were in place.

He also requested copies of the draft federal air marshal agreement with Cuba.                 

In a statement to FoxNews.com, a TSA spokesman said while it does not comment on particular security arrangements, the agency is working with Cuba to ensure there is a federal air marshal presence on flights when necessary.

"Based on several years of security assessments and routine public charter air service between the United States and Cuba, TSA is confident that all commercial flights from points of origin in Cuba to the United States meet international standards and additional security measures that are required by the United States Government,” the spokesman said.

American Airlines, one of the airlines running flights to and from Cuba, objected to the assertions in Rubio’s letter.

“We don’t speak about security, but the safety of our passengers, our people, and our equipment is of the utmost importance and we do not use use airports that do not meet the highest standards of safety for scheduled or chartered flights,”  a spokeswoman for American Airlines told The Miami Herald.

FoxNews.com's Adam Shaw contributed to this report.