U.S. President Donald Trump's tax reform could bring almost $2 trillion back to the United States as U.S. firms repatriate cash piles from foreign affiliates, a U.N. report said on Monday.

Ending the incentive to hoard cash overseas could produce a stimulus effect in the United States, and Trump has credited the tax reform with spurring a $350 billion investment plan by Apple.

"Now is the perfect time to bring your business, your jobs, and your investments to the United States of America," Trump told the World Economic Forum in Davos last month.