4/12/2018 1:49 PM PDT

Donald Trump has a sixth child nobody knows about -- a kid he had with his former housekeeper ... according to a stunning revelation by a doorman who used to work at Trump Tower.

Dino Sajudinhas just doubled down on his claim, saying ..."I can confirm that while working at Trump World Tower I was instructed not to criticize President Trump's former housekeeper due to a prior relationship she had with President Trump which produced a child."

Sajudin also admits he had a confidential agreement with The National Enquirer about the story of Trump fathering a child out of wedlock in the late '80s.

Earlier Thursday, a report came out saying the Enquirer paid $30,000 for Sajudin's story in order to bury it ... which is similar to allegations made by Karen McDougal regarding her story of having an affair with Trump. The outlet says after investigating it determined Sajudin's claim was false.

The Trump Organization also denied his claims.

If the story turns out to be true, it would mean the Prez has a child around 30 years of age ... which would put him or her older than Tiffany but younger than Eric.

See more here:

Trump Tower Doorman Claims Donald Trump Had Child with ...