The End of Oulipo? : An Attempt to Exhaust a Movement by Lauren Elkin & Scott Esposito (2013) claims that “Georges Perec … wrote a palindrome of over 5,000 words …” (p. 15, also mentioned on p. 25). However, this is wrong, unless these authors have access to an extraordinarily surprising never-before published palindrome of Perec’s. His long palindrome does not have this many words.
In 1980, Hachette published Perec’s La Clôture et autres poèmes, which contains “Le Grand Palindrome,” written in 1969. “Le Grand Palindrome” is also online; it is posted on another page without its title but with a declaration that the palindrome is 1247 words long.