U.S. President Donald Trump asked Congress on Tuesday for a loan of $4.9 billion to help the cash-strapped Puerto Rican government pay urgent bills as the U.S. territory struggles to recover from Hurricane Maria, an administration official said.

The request came as the oversight board charged with resolving Puerto Rico's debt crisis warned the U.S. territory was at risk of being unable to pay for essential services such as salaries for teachers, first responders and health care providers.

"The best estimate of the Financial Oversight and Management Board (FOMB) and government is that the commonwealth will run out of money at the end of this month," the board told U.S. Treasury Secretary Steven Mnuchin in a letter on Tuesday evening.