Quinton de Kock says he has too much on his plate to be South Africa Test captain on a long-term basis.

The Proteas' white-ball skipper this month agreed to lead his country in the longest format for the 2020-21 season.

De Kock will take on the duties for the encounters with Sri Lanka, Pakistan and Australia, replacing Faf du Plessis after the batsman stepped down in February.

Wicketkeeper-batsman De Kock ruled out staying on as captain, but is happy to fill in until a full-time successor to Du Plessis is appointed.

"When they [the South Africa selectors] told me the situation that we were in, I understood where they were coming from," De Kock said ahead of the first Test against Sri Lanka, which starts on Boxing Day.

"Obviously, I didn't accept it immediately. I did think about it and I understood, it's just for now. For this season. It's not a long-term thing.

"It's just [until] when we get someone who really puts up their hand, they will take over. The guys are looking for a long-term leadership role. I won't be doing that.

"There does seem a lot on my plate but I am quite happy to do it for now."

De Kock revealed he will retain the gloves in Test cricket, so it appears Kyle Verreynne will have to be patient before he is handed a debut.

"I wasn't going to keep in the ODIs against England. We were going to give someone else a chance and now that I am looking after the Test team, we are looking at ways to get a lot of things off my shoulders," De Kock said.

"But in Test cricket, I need to be there as keeper."