An Ontario teachers’ union representative is calling on the Toronto District School Board to investigate the online conduct of one of their trustees after he posted a series of controversial tweets about the LGBT community and insulted a city councillor.

In a letter to the TDSB, Doug Jolliffe, president of the Ontario Secondary School Teacher’s Federation District 12, expressed “grave concerns” over the online conduct of Scarborough trustee Sam Sotiropoulos, saying he has engaged on Twitter in “harassing debate” with TDSB employees, city councillors and others.

The letter, which was posted on OSSTF Toronto’s Facebook page Friday afternoon, was addressed to TDSB Chair Chris Bolton and Director of Education Donna Quan.

Sotiropoulos has come under fire in recent days over a series of tweets he posted relating to public nudity at Toronto’s Pride parade, and student inclusivity.

On Thursday, tempers flared again when Sotiropoulos referred to Coun. Shelley Carroll as a “windbag” during an exchange over Twitter.

In the letter, Jolliffe accused Sotiropoulos of engaging in “direct” and “systemic” discrimination, and harassment, and in doing so, violated the TDSB’s human rights and workplace harassment policies, and the Occupational Health and Safety act.

He also said Sotiropoulos should be held accountable under the TDSB’s Online Code of Conduct by virtue of his role as an elected official, and given that his personal Twitter account “clearly identifies his role as a TDSB trustee.”

Jolliffe called on the chair to commence an investigation to determine if Sotiropoulos has breached relevant school board policy or legislation.

In an interview Thursday, Sotiropoulos defended his actions, saying he was being “bullied” online after last week questioning the appropriateness of public nudity during Toronto’s annual Pride parade.

He claimed to be the victim of “homosexism,” which he defined as discrimination against a heterosexual person by members of the LGBT community.

Sotiropoulos also stood his ground over the “windbag” tweet, saying he was responding to a disparaging tweet from Carroll.