Koloane, who is the South African Ambassador to the Netherlands, was testifying at the judicial commission of inquiry into state capture on Tuesday.

"I abused the power of my office in putting pressure on defence officials to expedite the processing of the flight clearance, but I did not have control of diplomatic channels," he told the commission that is headed by Deputy Chief Justice Raymond Zondo.

The Gupta family landed a commercial aircraft at the air force base without permission. It carried about 200 guests who were invited to attend the family's lavish wedding at Sun City.

Zondo asked Koloane what had transpired on Monday during his testimony when he said he could not recall certain information because it happened six years ago, adding the Gupta aircraft landing at Waterkloof was something that had been talked about for a long time.

He also asked Koloane how he could have forgotten that he wrongly used the names of former president Jacob Zuma and two other ministers to pressure officials to speed up the flight clearance process.

"How is it possible that having been involved in something so big you would forget?"  

Koloane replied: "First of all, I can only say I'm human, like everybody else. 

"There are certain things that are pleasant memories that you want to linger on for the rest of your life, and there are some that you want to forget and close the door on them and never ever get back to them in your life.

"We tried to find, to go through therapy for me and my wife and my children in particular, to try and forget about some of these things.

"I think maybe it's just the refusal of the memory bank to deal with some of these realities because they do not bring anything but unnecessary pain to me, my wife and my children," he said. 

The commission continues on Wednesday, focusing on Transnet-related testimony.