A Victorian state school employee is being investigated after he brought firearms into class, baked a cake with a swastika on it and let a student dress up in his Nazi hat.

During a history lesson on World War II, the Dromana Secondary College employee also allowed students to play with a replica Zyklon B gas canister, which resembled one that would have been used to kill Jews.

The students were given Nazi uniform to wear.

The items were part of his personal collection of military memorabilia. Students also handled rifles, helmets and uniforms once worn by Australian troops.

The Education Department is investigating the incident, which it described as a “serious error of judgement”.