A lewd note allegedly from US President Donald Trump wishing late sex offender Jeffrey Epstein happy birthday in 2003 – and alluding to their "wonderful secret" – was released on Monday by Democratic lawmakers, though the White House quickly denied its authenticity.

Democrats on the US House Oversight Committee, which is probing the handling of a criminal investigation into the disgraced financier, published the letter on social media after it was delivered by Epstein's estate.

The note is situated on the sketched outline of a nude woman, and was allegedly part of a book compiled of letters from Epstein's friends by his associate Ghislaine Maxwell, for the financier's fiftieth birthday.

The note is comprised of a short dialogue between "Donald" and "Jeffrey."

"A pal is a wonderful thing. Happy Birthday – and may every day be another wonderful secret," the note ends, followed by Trump's signature, which takes the place of pubic hair on the nude outline.

Trump, a longtime friend of Epstein, denies any wrongdoing and sued the Wall Street Journal for US$10 billion after it originally reported the existence of the letter, insisting that he had never sent it.

White House deputy chief of staff Taylor Budowich denounced the release, saying the signature on the letter is not Trump's and alluded to Trump's lawsuit against the Journal's parent company, News Corp.

"Time for @newscorp to open that checkbook, it’s not his signature. DEFAMATION!" Budowich posted on X.

Epstein, a wealthy financier with high-level connections around the world, was found dead in his New York jail cell in 2019 while awaiting trial for alleged sex trafficking of underage girls recruited to provide him with sexual massages.

Trump's supporters have been obsessed with the Epstein case for years and held as an article of faith that "deep state" elites were protecting Epstein associates in the Democratic Party and Hollywood.

But many of his supporters have been up in arms since the FBI and Justice Department said in July that Epstein had committed suicide, did not blackmail any prominent figures, and did not keep a "client list."

Trump has repeatedly attempted to bury the controversy amid growing questions about the extent of his own relationship with the sex offender. (Agencies)