The federal government's response to hurricanes Harvey and Irma on the mainland was faster and more "generous" — in terms of resources and funds — than its assistance to Puerto Rico before and in the aftermath of Hurricane Maria, according to a newly released study.

By analyzing federal spending estimates and other statistics, researchers at the University of Michigan found significant differences between the aid Texas and Florida received after the two states were hit by powerful storms and the assistance dispatched to Puerto Rico when María struck the island and U.S. territory in the fall of 2017.

"The federal government responded on a larger scale and much more quickly across measures of federal money and staffing to Hurricanes Harvey and Irma in Texas and Florida, compared with Hurricane Maria in Puerto Rico," researchers wrote in the report. "The variation in the responses was not commensurate with storm severity and need after landfall in the case of Puerto Rico compared with Texas and Florida."

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According to the study, within nine days of landfall in the U.S. for Harvey and Irma, survivors in Texas and Florida received approximately $100 million in Federal Emergency Management Agency (FEMA) funds, while María survivors received about $6 million in FEMA assistance in the same amount of time.

Researchers also detailed disproportionate levels of federal staffing for the three disaster responses. At its peak, 19,000 federal employees were stationed in Puerto Rico a month after María made landfall, compared to the peak in Texas of 31,000 emergency workers. Puerto Rico also received less food, water, tarps and helicopters than Texas and Florida, according to the study.

The report's authors added that "geographic limitations" do not fully explain the "magnitude of this variation" in the different responses. The Trump administration has argued that supplies and goods took longer to reach Puerto Rico because the territory is not part of the contiguous U.S. In September 2017, President Trump said, "This is an island, surrounded by water. Big water. Ocean water" to defend his government's relief efforts in Puerto Rico.

The office of Governor Ricardo Rosselló seized on the report to continue its criticism of the Trump administration's handling of recovery efforts and to denounce the "colonial" treatment of the U.S. territory, home to approximately 3.2 million U.S. citizens.

"The study released today is further evidence that the federal government dragged its feet during the biggest disaster in our recorded history, which took the lives of almost 3,000 citizens," Carlos Mercader, executive director of the Puerto Rico Federal Affairs Administration, which represent's the island's government in the U.S., wrote in a statement to CBS News.

"We can only hope that the mounting evidence serves to improve the federal government's response during the next natural disaster," Mercader added. "Nevertheless, as long as we remain a mere territory without any say in our government, we will always get the short end of the stick in our fundamentally imperfect relationship with the United States."

Asked about the study, a FEMA spokesperson referred CBS News to an agency report published last summer in which FEMA conceded it was understaffed and unprepared to respond to the devastation caused by María. In the report, the agency also signaled it underestimated the amount of resources, including food supplies, that the island needed in the storm's aftermath.

After a follow-up inquiry, FEMA press secretary Elizabeth Litzow defended the agency's work in Puerto Rico, which she said was "the largest and longest commodity delivery mission in the agency's history." She called the study's finding that the federal response for Maria was slower than relief efforts for Harvey and Irma "absurd."

"An ideal response to any disaster is one that is federally supported, state managed and locally executed. FEMA's ability to provide support in disasters builds on, and is subject to, the capacity of the state, territorial, tribal & local governments," Litzow wrote Tuesday night in a statement to CBS News. "There were real challenges in Puerto Rico that had to be overcome — including aging infrastructure, a decayed power grid and liquidity issues."

The White House didn't respond to CBS News' request for comment.

You can read FEMA's full statement to CBS News below: