Ben Affleck has admitted he was “embarrassed” about a slave-owning ancestor and says that’s why he lobbied television chiefs to hide his story in a documentary about his heritage.

The Hollywood star said he regretted trying to influence what went into the programme and was now glad that his family history would be part of the discussion about the impact of slavery in America.

“I didn’t want any television show about my family to include a guy who owned slaves,” Affleck said in a statement posted to Facebook on Tuesday evening. “I was embarrassed. The very thought left a bad taste in my mouth.”

Affleck spoke out after hacked emails from film studio Sony Pictures Entertainment, leaked online, revealed that he had asked producers of the television programme Finding Your Roots to suppress details of the ancestor. The revelations have provoked a censorship scandal in the US: the programme’s producer, Henry Louis Gates, a history professor at Harvard, had to issue a statement insisting he retained “editorial control”.

Affleck, meanwhile, was accused by commentators of failing to face up to the skeletons in his family’s past and avoiding an issue which still looms large on America’s cultural landscape.

In his statement, Affleck said that Gates, whom he referred to as Skip, decided what went into the show, but admitted: “I lobbied him in the same way I lobby directors about what takes of mine I think they should use.”

Responding to comments below his apology, he denied accusations of censorship, adding that Gates had told him that details of his slave-owning forebear had been omitted from the first cut because there wasn’t much detail. There was only “a name and no details”, wrote Affleck, “so he wasn’t going to go with it to begin with”.

But that claim appears to contradict some details of Gates’s emails with Sony’s chief executive, Michael Lynton, where he seems to argue that agreeing to Affleck’s request “would be a violation of PBS rules, even for Batman”.

Public Broadcasting Service has launched an investigation into the revelations to “determine whether or not all of PBS’s editorial standards were observed”, according to a statement released by the broadcaster on Tuesday and seen by the Hollywood Reporter.

Affleck pointed out that Finding Your Roots was not a news programme but “a show where you voluntarily provide a great deal of information about your family, making you quite vulnerable”. He said the assumption was that producers would respect that participants chose to took part and would not want details aired that could embarrass them or their families. However, he devoted to final paragraph to an apology for trying to hide his family’s slave-owning past.

He wrote: “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. It is an examination well worth continuing. I am glad that my story, however indirectly, will contribute to that discussion. While I don’t like that the guy is an ancestor, I am happy that aspect of our country’s history is being talked about.”

The emails between Gates and Lynton were published online by WikiLeaks. It is not clear how the pro-transparency group acquired the emails, which it published with up to 30,000 others involving Sony. They are believed to be part of a huge batch stolen last summer in a cyber-attack blamed on a group affiliated to North Korea.

Julian Assange, the editor-in-chief of WikiLeaks, issued a statement saying the leak of the exchange about Affleck was justified because it showed the inner workings and influence of a multinational media giant.

Despite a number of damaging revelations about Sony Pictures executives, the studio’s Japanese parent company, Sony, said it had lost less money than expected in the past financial year. On Wednesday, it revised its consolidated forecast for the year ending 31 March to show higher sales and lower losses than anticipated, trimming its expected net losses from $1.42bn (£949m) to $1.05bn (£702m), Variety reported.