Cape Town - Proteas skipper Faf du Plessis couldn't hide his disappointment with the news that fast bowler Duanne Olivier had signed a Kolpak deal with Yorkshire.

Olivier dropped the bombshell last week that he had signed a three-year Kolpak contract with the English county.

It is a move that effectively ends his international career after 10 Tests and two ODIs.

Du Plessis admitted to reporters this weekend that the timing of Olivier's Kolpak deal upset him.

"Duanne put himself to be one of the three top seamers in our team. Once again it's the timing that disappoints me most, it reminds me of Kyle Abbott two-three years ago," said the Proteas captain.

"I care for the players, when they earn their spot in the team, you want them to run with it for a while and get the best out of themselves from an international point of view.

"It's a case of playing a couple of Test matches and was then out of the Test team - understandably so because the top dogs were back. I think in that period, your decision-making progress starts happening," he said.

"You look at the last month or two and we go: 'How can you sign a Kolpak? You're playing and doing well?' But I think his decision-making happened a lot sooner than that. What unfolded this summer was great for him but by then he was already - without us knowing - halfway committed there.

"Every guy makes that decision based on his personal reasons, I do understand why he done it. But once again, we as South African cricket lose a great bowler," said Du Plessis.

Olivier's contract is reportedly worth R2.7 million per season, and dwarfs the two-year R900 000 per season contract offered to the 26-year-old by Cricket South Africa (CSA).

Du Plessis believes that this will always be a challenge for CSA, if structures are not put in place.

"I think to their credit Cricket South Africa moved in the right direction with it. I feel like there's more conversations done behind the scenes with the players and I know with Duanne those conversions happened," he said.

"CSA offered him a two-year contract... It's the challengers that we've faced that the broader game of cricket is bringing: it's either Kolpak for other players or the T20 circuit.

"We, as CSA, need to put in plans and structures because otherwise we'll potentially lose more."