A teacher at Trinity Grammar School in Sydney’s inner west has been arrested over alleged online grooming.

Ben Fordham has revealed Strike force detectives arrested the 39-year-old man at the school in Summer Hill, just before 3pm yesterday.

Police will allege in court the man believed he was speaking to a 13-year-old girl and engaged in conversations about sexually explicit acts and sent sexually explicit images.

But it was an undercover detective with Strike Force Trawler that he was communicating with.

It will also be alleged that the man was engaging in these conversations on his mobile phone while at work.

The teacher has been charged with use of carriage service to send indecent material to a person under 16, and use carriage service to solicit child abuse material.

He was refused bail to appear before Burwood Local Court today.

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