Independent Democrats (ID) leader Patricia de Lille will join the Western Cape government as social development minister, provincial Premier Helen Zille said in Cape Town on Friday.

De Lille told journalists at a press conference in the provincial legislature that De Lille would replace Ivan Meyer, who would become cultural affairs and sport MEC.

"The good news is that Patricia de Lille will be joining the cabinet in the Western Cape as minister of social development," Zille said.

"Ms De Lille will be sworn in as an MPL at the first opportunity and will then be sworn in as minister in the provincial government."

Current cultural affairs and sport MEC Sakkie Jenner will be made a committee chairman in the provincial legislature once the review of the structure is complete.

Zille said that current community safety MEC Lennit Max would move to the National Assembly to become an MP. He will be replaced as MEC by MP Albert Fritz.

"Mr Lennit Max has agreed to swap with Albert Fritz in the National Assembly and Mr Fritz has agreed to swap with Lennit Max."

Zille said that the decision was, however, awaiting approval from the DA federal executive.

She said that Fritz was perfectly suited to the job and had been impressed by his "oversight role on the function of police".

She said she had given Max several options about his future.

"I gave Mr Max some options and he chose the option of going to Parliament."

Zille refused to give reasons for swapping Max, saying it was her "right to exercise her judgement".

"I'm grateful Mr Max responded in the way he did," she said.

De Lille, who was seated next to Zille at the press conference, said it was an honour for her to take up the role.

"Social development is my passion. For 24 years I've been fighting for the poor and the downtrodden. You won't find me in an office, I will be out there dealing with the problems on the ground."

De Lille joked that MPs would be glad to see the back of her revelations about their travel expenses. She revealed on Thursday that several MPs had been running up exorbitant travel accounts.