Puerto Rico's Institute of Statistics is suing the island's health department and demographic registry to obtain data on the number of deaths following Hurricane Maria as a growing number of critics accuse the government of lacking transparency.

The lawsuit was filed Thursday, the same day that Puerto Rico Gov. Ricardo Rossello told CNN that there would be "hell to pay" if officials didn't release mortality data.

A spokeswoman for the island's health department, which oversees the demographic registry, did not immediately respond to a message for comment.

Institute of Statistics Director Mario Marazzi-Santiago said Friday that the data is urgently needed so Puerto Rico's government can help prevent deaths in the event of another hurricane. Many believe the official death toll of 64 is an undercount.