The Puerto Rico Department of Health released data late Friday that shows there were at least 1,400 additional deaths on the island in the months after Hurricane Maria as compared to the prior year. It was the first time in months that the territorial government has released mortality data, and the numbers indicate that the death toll from the hurricane was far greater than the official tally of 64.

The data show that deaths were far higher in September and October than in the prior two years. According to the new data, 3,040 people died in Puerto Rico in October 2017 - the first full month after the devastating storm hit on Sept. 20 - an increase of 680 over the prior year.

The government tallied 11,459 deaths from September to the end of December as compared to 10,062 during the same period in 2016, a 14 percent increase. The agency's numbers do not certify whether those 1,400 additional deaths are attributable, directly or indirectly, to the hurricane, describing only the number of death certificates the Puerto Rico government collected each month. The agency did not provide any additional information to put the data in context.

Up until Friday, the agency had declined to release finalized mortality data while its investigators work with researchers from George Washington University to review territory archives.

The new data was released three days after Harvard researchers released the results of a study that found the mortality rate was much higher than previously known and estimated that at least 4,600 people died in the nearly three months after the storm - a 62 percent increase in the mortality rate compared with 2016.

The study, published in the New England Journal of Medicine this week, found that health-care disruption for the elderly and the loss of basic utility services for the chronically ill had significant impacts on the mortality rate.

The article said that "health care disruption is now a growing contributor to both morbidity and mortality in natural disasters," and has occurred following 2005's Hurricane Katrina in New Orleans; Superstorm Sandy, which hit the Atlantic Coast in 2012, and hurricane Harvey, which struck the Houston area in August 2017, and Irma, which battered Puerto Rico two weeks earlier than Maria.

Hurricane Maria caused widespread damage across the U.S. territory, dramatically affecting infrastructure. Many roads were impassable, bridges were washed out, and much of the island remained without power for six months. Residents have said it was difficult to communicate, emergency services were hampered, and hospitals and morgues were overwhelmed.

Puerto Rico's government faced immediate scrutiny after initially reporting that 16 people had died as a result of the storm. That number kept rising until early December, when authorities said 64 had died. The official tally has come under intense criticism as residents, news organizations and official studies have placed the toll at far higher levels.

The Harvard study authors said that like reporters and news organizations suing the Puerto Rico government for access, their requests for official data also were denied. Gov. Ricardo Rosselló told CNN that he was unaware of his government withholding data and that there would be "hell to pay" if that information wasn't released.

Wanda Llovet, chief of the Department of Health's Demographic Registry, defended her agency on Friday, saying it provided fatality information in "accordance with the public policy of transparency," according to a statement that accompanied the data release.

The data shows a much smaller increase in overall deaths than those estimated by the Harvard study, which included surveys of thousands of Puerto Rico residents. George Washington University officials said their government-funded investigation, which will look at fatalities up to February, has taken longer than expected; GW plans to release a statistical analysis using the demographic data sometime over the summer.