Hollywood's actors union launched disciplinary action against outgoing US President Donald Trump on Monday, which could lead to the former "Apprentice" star's expulsion.

SAG-AFTRA "voted overwhelmingly to find probable cause of a violation" of its constitution by long-time member Trump, whose screen credits include "Home Alone 2."

The guild's disciplinary committee will now examine Trump's role in the January 6 mob attack on the US Capitol.

Thousands of Trump supporters stormed the Washington building following a speech by the president in which he repeated his false claims to have won the election. At least five people died in the mayhem.

"Donald Trump attacked the values that this union holds most sacred -- democracy, truth, respect for our fellow Americans of all races and faiths, and the sanctity of the free press," said SAG-AFTA president Gabrielle Carteris. 

The committee will also examine Trump's "reckless campaign of misinformation aimed at discrediting and ultimately threatening the safety of journalists," according to a statement 

SAG-AFTRA also represents thousands of broadcast journalists among its 160,000 members.

"There's a straight line from his wanton disregard for the truth to the attacks on journalists perpetrated by his followers," said Carteris.

"Our most important role as a union is the protection of our members," added national executive director David White. 

"The unfortunate truth is, this individual's words and actions over the past four years have presented actual harm to our broadcast journalist members."

The non-partisan SAG-AFTRA in 2018 issued a statement vowing to defend "the basic rights of a free and independent press," after CNN White House correspondent Jim Acosta had his access revoked following a tense exchange with the president.

If found guilty, Trump could face a fine and suspension or expulsion from SAG-AFTRA, which typically brings a pension as well as benefits including early "screener" access to upcoming films. 

According to entertainment website Deadline Hollywood, Trump joined SAG-AFTRA's predecessor organizations in 1989. He has also appeared in 2001 film "Zoolander," and in television's "The Fresh Prince of Bel-Air" and "Sex and the City," playing himself.