The Church of England should have done more to investigate allegations that young boys were abused by a former colleague of the archbishop of Canterbury, its top safeguarding official has said.

The archbishop, Justin Welby, said he was told in 2013 about the claims made against John Smyth, with whom he had worked in the 1970s at a Christian holiday camp. Police had been notified of the allegations at the time, he said in a statement.

Channel 4 News reported that Smyth, the chairman of the Iwerne Trust, which ran the camps for public school pupils, had been accused of decades of abuse. Three people claimed they had been beaten by him.

Graham Tilby, the church’s national safeguarding adviser, said: “Clearly, more could have been done at the time to look further into the case.”

Speaking on LBC Radio on Thursday, Welby said he had been “completely unaware” of any abuse when he worked at the camp.

“I was at that particular camp in the mid-70s. I was young then – 19 to 21 or 22 – and I was completely unaware of any abuse. I never heard anything at all, at any point. I didn’t have the slightest suspicion at all.

“As I recall him, he was a charming, delightful, very clever, [a] brilliant speaker. I wasn’t a close friend of his, I wasn’t in his inner circle or in the inner circle of the leadership of the camp, far from it.

“And then I went off to work in France in 1978, which is when I am told the abuse began. It may have been earlier or later, I don’t know, and I was abroad during the time the report was done and had no contact with them at all.”

The archbishop said he was first informed of the alleged abuse in late 2013 or early 2014.