The Bloomberg administration’s policy of allowing charter schools to share building space with traditional public schools has not led to a significant spike in class size, according to study released today by a charter-school group.

Eva Moskowitz’s Success Charter Network looked at four years of data for all K-to-8 schools — those where charters and traditional public schools shared space, and others where they didn’t.

It showed that class size at traditional public schools that shared spaced with charters increased by an average of 1.1 students from 2007 through the current school year.

During the same period, the average class size increase at traditional public schools that did not share space with charters increased by 1.2 students, the report said.

The study rebuts the contention of charter-school opponents who claim that co-locating charters in city buildings will trigger huge increases in class sizes.