Footage of Donald Trump on the set of his reality TV show The Apprentice remains locked away from public view, despite cast and crew alleging he frequently used lewd and sexist language during shooting.
Media have repeatedly tried to contact the executive producer of the program, Mark Burnett, after Friday's release of a separate recording on which the Republican presidential nominee brags about groping women.
That recording was made in 2005 by a different show, Access Hollywood, as Trump prepared to appear on a soap opera.
The Access Hollywood comments have led to widespread condemnation, with several Republican members of Congress calling on Trump to abandon his White House campaign.
In a video posted by Trump early on Saturday, he apologised but also called the recordings a distraction. He later told a pair of newspapers he would never quit the race.
Access Hollywood said on Friday it was an Associated Press story published on Monday about Trump's frequent use of lewd and sexist language as host of The Apprentice that led it to dig through its archives and turn up its own footage.
NBC spokeswoman Rebecca Marks told AP the network had only licenced The Apprentice from Burnett and if it did have footage in storage it could not legally release it anyway.
A former crew member on The Apprentice, who spoke on condition of anonymity after signing a non-disclosure agreement, said on Friday Burnett guarded the show's footage carefully, at the time it was being produced, to prevent spoilers that would reveal in advance which contestant had won the competition reality show.
"The Apprentice footage was super vaulted stuff to keep it from getting into anyone's hands,'' said the former crew member. "The game-show aspect meant that the footage was locked down super securely.''
AP reported on Monday that during his years hosting The Apprentice, Trump repeatedly demeaned women with sexually tinged comments, rated female contestants by their breast size and commented about which ones he would like to have sex with. He made one such comment less than a year after marrying his third wife, Melania, in January 2005.
Burnett, an Emmy winner, is a British-born television producer based in Los Angeles. In December, he was named president of MGM Television and Digital Group.
The Apprentice debuted in January 2004 and ran for 14 seasons, some within the same year and some as The Celebrity Apprentice.
Trump and NBC parted company in 2015 after Trump made comments about Mexican immigrants that network executives deemed racist.
