One of Japan's best-known contemporary artists is locked in a fight with a public museum over claims it has threatened to withdraw works critical of the conservative government.

Makoto Aida said the Museum of Contemporary Art Tokyo told him to remove the pieces from an exhibit that started last week because they were "not suitable" for kids, but the museum countered that it just asked him to "modify" his creations.

"I was told that the works were not appropriate and that they wanted me to remove them," the artist said this week.