Hollywood star Ben Affleck says he was "embarrassed" upon learning he had slave-holding ancestors, and regrets asking US television producers to censor that fact from a program about his family's past.

Affleck was featured late last year in the television program "Finding Your Roots," a nationally broadcast program that profiles the family histories of well-known Americans.

The actor -- known as an ardent supporter of liberal causes -- was dismayed to learn that in addition to a forbear who was a Revolutionary War hero, he also had a long-ago relative who was a slavemaster.

"After an exhaustive search of my ancestry for 'Finding Your Roots,' it was discovered that one of my distant relatives was an owner of slaves," Affleck wrote in a Facebook message posted late Tuesday.

"I didn't want any television show about my family to include a guy who owned slaves. I was embarrassed. The very thought left a bad taste in my mouth," he said.

"I regret my initial thoughts that the issue of slavery not be included in the story," Affleck wrote.

The actor added that he has learned an important lesson about trying to cover up one's past.

"We deserve neither credit nor blame for our ancestors and the degree of interest in this story suggests that we are, as a nation, still grappling with the terrible legacy of slavery," he said.

The revelations that Affleck had lobbied the television network PBS to edit out the slave-owner relative in his ancestry was first revealed in emails leaked by WikiLeaks earlier this month.

The message published by WikiLeaks was part of a trove of embarrassing emails, film scripts and other internal communications that were accessed during a massive hack of Sony in 2014.

Affleck stars as Batman in the upcoming "Batman v Superman: Dawn of Justice" movie. He is also known for supporting an array of causes including the Eastern Congo Initiative.

The TV program's host, Harvard professor Henry Louis Gates, discussed with a third party the "dilemma" of having been asked to edit out Affleck's slavemaster forbear.

The program has profiled the histories of "four or five of our guests this season (who) descend from slave owners," he wrote in one of the leaked emails.

"We've never had anyone ever try to censor or edit what we found. He's a megastar. What do we do?"