The ban, instituted after Christmas last month when local children and adults were seen wearing clothes "that resemble Santa Claus", raises fresh concerns of religious restrictions after last April's announcement of the introduction of a penal code that will eventually include penalties such as the severing of limbs and death by stoning.
A spokesman declined to comment directly on the ban, but referred to a December 27 statement in which the ministry said the act of publicly marking non-Islamic rituals or festivities "can be seen as propagations of religions other than Islam."
"Believers of other religions that live under the rule of an Islamic country - according to Islam - may practice their religion or celebrate their religious festivities among their community, with the condition that the celebrations are not disclosed or displayed publicly to Muslims," the statement said.
"Muslims should be careful not to follow celebrations such as these that are not in any way related to Islam... And could unknowingly damage the faith of Muslims."
The latest move comes after Brunei's all-powerful Sultan Hassanal Bolkiah announced in April that he would push ahead with the introduction of a new criminal code which sparked rare domestic criticism of the fabulously wealthy ruler as well as international condemnation.