US entertainment giant Disney was forced to apologize after one of its Japanese-language tweets was criticized for being insensitive as the country commemorated the 70th anniversary of the Nagasaki atomic bombing.

The company's Japanese unit, referencing the animated film Alice in Wonderland, took to social media on Sunday with a message about the movie's well-known "unbirthdays".

The original English tweet wished followers a "very merry unbirthday".