Updated at 6:35 p.m. Oct. 12

The U.S. Treasury Department is investigating whether Florida Gov. Ron DeSantis misused federal coronavirus pandemic recovery money to send migrants from Texas to Martha’s Vineyard last month, in what appears to be the first federal probe into the incident.

The oversight arm of the agency said it is investigating the use of over $600,000 in pandemic relief funds by the Republican governor’s administration for the chartered flights, in addition to its usual audit work on whether the funds are being proctored properly, according to an Oct. 7 letter to seven Massachusetts legislators.

"As part of our oversight work of the Coronavirus Relief Fund established by the CARES Act, we have already sought information from Florida about appropriate use of that fund," wrote Deputy Inspector General Richard Delmar. The office had no further comment beyond the letter, and DeSantis’ office didn’t return requests for comment.

The news comes in response to a request led by Sen. Ed Markey’s office and signed by six other Massachusetts legislators calling on the inspector general to pursue the matter.

At issue is a total $12 million approved this summer by the Florida Legislature for a migrant relocation program, allegedly using interest earnings associated with COVID-19 relief funding. In late September, DeSantis paid for charter flights that brought about 50 mostly Venezuelan migrants from Texas to Martha's Vineyard, without alerting any aid groups or government agencies in Massachusetts that they would be coming.

Delmar wrote that his office will “specifically confirm” whether interest from the State and Local Fiscal Recovery Fund for the pandemic was “utilized by Florida related to immigration activities.”

“Sen. Markey applauds the swift response from the Treasury's Office of the Inspector General for the sake of the migrants who are lured onto charter planes under false pretenses, and for the commendable commonwealth residents who rally together to offer support to them,” said spokesperson Rosemary Boeglin. “We hope that this investigation sheds light on whether Gov. DeSantis misused funds that were intended for COVID relief for Floridians.”

Markey is also asking the Transportation Department to assess whether consumer protections were violated when the migrants were flown under false pretenses to Massachusetts by Ultimate Jet Charters.

Delmar said the scope and timing of the Treasury review could be affected by "legislative and judicial challenges to the use of the funds."

The Florida governor's office claims that their Office of Policy and Budget spoke with the Treasury's Office of the Inspector General weeks ago about using these funds for transporting immigrants.

If the Office of the Inspector General determines Florida misused the funds intended for coronavirus recovery, it could demand repayment, according to a provision of the CARES Act.

A legal challenge filed last month by Lawyers for Civil Rights on behalf of the migrants also suggested that DeSantis misused COVID-19 relief funding.

“It's one of the claims in our lawsuit that Gov. DeSantis has misused emergency funds that were meant to address a public health crisis in order to violate the constitutional rights of our clients," said Oren Sellstrom, litigation director for the group.

Other immigration attorneys are helping the immigrants figure out how to apply for asylum, in addition to pursuing visas reserved for victims of a crime.

This story was updated to include comment from the Florida governor's office.