Director Todd Phillips said Thursday Gibson's role was being recast because some of the actors and crew didn't want him involved in the project, which features Bradley Cooper, Neeson's "A-Team" co-star.
People.com said Neeson later confirmed he would play the part instead of Gibson.
"I just got a call to do a one-day shoot on 'Hangover 2' as a tattooist in Thailand, and that's all I know about it," Neeson told Daily Variety. "I just laughed my leg off when I saw 'The Hangover.' I was shooting in Berlin earlier this year and rented it on the hotel TV."
Teacher apologizes for showing sexual image of herself in class
Dennis Rodman pledges to end trips to North Korea