South African Revenue Service (Sars) Acting Commissioner Mark Kingon has apologised "unreservedly" to the people of South Africa for leadership failures at the tax service, saying they "fell short of the highest standards."

Giving evidence at the Nugent Commission of Inquiry - which is probing matters of tax administration and governance at Sars - a visibly emotional Kingon held back tears as he read his apology.

"I would like to say sorry on behalf of Sars leadership, I would like to say sorry to the president, the minister of finance, former officials and their families for the fear and pain they were put through."

"I would like to say sorry for falling short of the highest standards," he said.

Kingon was appointed to the position after the suspension of his boss Tom Moyane in March. His term has twice been extended by 90 days while Moyane’s future is being decided.

He began his testimony on Friday morning by acknowledging that the revenue collection agency continues to be in a "tumultuous" position, adding he hoped the organisation never again finds itself in the same situation.

"We need visionary leaders, and we don't have that," he said adding that the agency's position keeps him awake at night.

"We need vision to take this place forward. The first part of healing is acknowledging that there is a problem."

His testimony continues.