Puerto Rico Governor Ricardo Rossello told CNN there would be "hell to pay" if officials do not release the death statistics.
The government released additional information Friday, saying an additional 1,397 overall deaths were reported in the aftermath of the storm, from September to December 2017, according to the Washington Post.
Officials have not released the cause of death in any of those cases.
A spokeswoman for the island's health department, which oversees the demographic registry, did not respond to the AP’s request for comment.
Many officials and people in Puerto Rico believe the official death toll of 64 from Hurricane Maria is severely underestimated.
In February, Puerto Rico announced that a team of experts from George Washington University would lead an independent review of the official death count.
The group’s preliminary report was due before hurricane season began June 1, but the team has been granted more time.