Tokyo, Japan - Barbenheimer memes have sparked anger online in Japan, the only country to ever have been attacked in wartime with nuclear weapons.

Barbie and Oppenheimer are the double bill of the summer and has been making a splash on the internet, but the online fun is having some unintended consequences.

Memes shared on social media combined images from both movies as part of the Barbenheimer phenomenon, with one showing Barbie the on the shoulders of Oppenheimer, against the backdrop of an apocalyptic blast.

"Do they know how many people died when that mushroom cloud appeared?... Don't have fun with the atomic bomb," said one irate Japanese social media user, using the hashtag #NoBarbenheimer.

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Around 140,000 people died in Hiroshima and 74,000 in Nagasaki when the US dropped atomic bombs on the two Japanese cities days at the end of World War II in 1945.

"We just want (the US) to know what kind of devastation the two atomic bombs caused before speaking, not just for Japan but also for the world," wrote another user.

The official account of the Barbie movie on X, formerly known as Twitter, replied to one of the memes, saying: "It's going to be a summer to remember" accompanied by a blowing kiss emoji.

The message, which on Tuesday was no longer visible, prompted Warner Bros. Japan, the local distributor of Barbie, to say sorry.

"We apologize to those who were offended by this series of inconsiderate reactions," Warner Bros. Japan said in a statement.

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The distributor also said the replies by the US official account were "extremely regrettable", adding they are urging the headquarters to "take appropriate action".

Barbie is due to be released in Japan later this month, but no date has been set for Oppenheimer. Both films have been major box-office successes.