Parti Keadilan Rakyat (PKR) president Datin Seri Dr Wan Azizah Wan Ismail is to replace her husband, Datuk Seri Anwar Ibrahim as the Pakatan Rakyat candidate in the Kajang state by-election.

Announcing her candidacy here today, Anwar, who is also PKR advisor, said Dr Wan Azizah was the most suitable candidate to replace him and the decision was agreed by the Pakatan leadership.

Prior to this, Anwar, who was tipped to contest in the state seat, had already started campaigning.

The Election Commission has fixed nomination day on March 11 and polling on March 23.

Last Friday, the Appeal Court sentenced Anwar to a five-year jail term after setting aside the High Court's decision in 2012, which found him not guilty of sodomising his personal aide, Mohd Saiful Bukhari Azlan, six years ago.

Following the court's decision, DAP national chairman Karpal Singh, who was also Anwar's counsel, said the opposition leader could not file his nomination papers for the Kajang by-election.

Asked on why Dr Wan Azizah was chosen as the candidate compared to other names, including secretary-general Datuk Saifuddin Nasution, Anwar said the selection was agreed by all quarters, including Saifuddin himself.

"I was keen to have Saifuddin but he was reluctant and wanted to be secretary-general. And in light of the current circumstances, Azizah is a suitable candidate," said Anwar.

Meanwhile when asked if she was chosen only as a 'seat warmer to Anwar,' Dr Wan Azizah said it was up to any quarters to assess.

"They can say whatever they like but what is more important is we carry on the struggle," she said.