SA's top prosecutor to leave in April

South Australia's Director of Public Prosecutions Adam Kimber will not continue in the role after his current term expires.

Attorney-General Vickie Chapman says Mr Kimber has advised her he will not be re-applying for his job when it becomes vacant in April.

"I would like to thank Adam Kimber on his past seven years as director of public prosecutions," Ms Chapman said in a statement on Thursday.

"This job is not an easy one and he has achieved quite a lot in his time in the role."

Mr Kimber declined to comment on his position but there was some speculation that his decision to leave was prompted by the government's move not to automatically reappoint him.

Opposition frontbencher Tom Koutsantonis questioned why the government would not want Mr Kimber to continue.

"The DPP is one of the most important and trusted positions in the state and effectively the DPP has just been sacked," Mr Koutsantonis tweeted.

Ms Chapman said the government would advertise for a new director in February.

"I wish Mr Kimber all the best in his future endeavours," she said.