Assumption College director Anant Prichavudhi has been ordered to stand aside pending a probe into alleged financial mismanagement.
The order was announced yesterday by the St Gabriel Foundation, which oversees Assumption College and 13 other Catholic schools.
Earlier, the foundation met Private Education Commission secretary-general Chanwit Tubsuphan along with the school's executives, teachers and alumni.
Brother Anant did not attend.
"He has told the foundation that he has done nothing wrong and will not resign," Bancha Saenghiran, who represents the St Gabriel Foundation, said.
However, the foundation has decided to suspend Brother Anant from work while a probe panel looks into allegations against him.
About 300 teachers and alumni protested against the school director on Friday.
They are concerned about his plans to merge the elementary section of Assumption College on Sathon Road with its secondary section in Bang Rak district.
Some staff fear they could lose their jobs as a result of the merger, although Brother Anant has assured them this will not be the case.