Officials in U.S. President Donald Trump's administration are exploring ways of challenging the tax-exempt status of nonprofits, the Wall Street Journal reported on Saturday.

Internal Revenue Service lawyers have been exploring whether they could change the rules governing how nonprofit groups can be denied tax-exempt status, the Journal said, citing people familiar with the matter.

The IRS and the U.S. Treasury did not immediately respond to a Reuters request for a comment.

The meetings started taking place shortly after the Trump administration appointed Andrew De Mello as the new top interim lawyer at the IRS, the report added.

Another senior IRS official, Gary Shapley, separately said in at least one meeting that he was giving priority to investigating the tax-exempt status of a select group of nonprofit organizations, the report added.

U.S. President Donald Trump said on Friday his administration would revoke Harvard University's tax-exempt status, returning to a threat he issued against it as part of his wider attack on elite universities he deems left-wing and anti-American.