A principal of a Florida school has been forced to resign after a parent complained that students were exposed to pornography.

The complaint arose from a Renaissance art lesson where students were shown Michelangelo's statue of David.

The iconic statue is one of the most famous in Western history.

But one parent complained the material was pornographic and two others said they wanted to know about the class before it was taught.

The lesson also included references to Michelangelo's "Creation of Adam" painting and Botticelli's "Birth of Venus".

Principal Hope Carrasaquilla of Tallahassee Classical School said she resigned after she was given an ultimatum by the school board to resign or be fired.

Local media reported that Ms Carrasquilla did not know the reason she was asked to resign, but believed it was related to the complaints over the lesson.

They also said Ms Carrasquilla had been principal for less than one year.

On Thursday, Florida's governor moved to expand a law that banned public schools from teaching sexual education and gender identity.

Teachers who violate the law face being suspended or losing their teaching licences.