President Jacob Zuma will on Thursday announce South Africa's new chief justice.

Zuma faced the arduous task of nominating a new chief a few months into his term, as current Chief Justice Pius Langa, at the helm of the judiciary since 2005, retires this month.

In August Zuma nominated Justice Sandile Ngcobo as his preferred candidate, to the chagrin of opposition parties who insisted the pick was unconstitutional.

By law, the president as head of the national executive, after consulting the Judicial Service Commission and the leaders of parties represented in the National Assembly, appoints the chief justice and his or her deputy.

The Democratic Alliance, the Congress of the People, the Inkatha Freedom Party and the Independent Democrats accused Zuma of failing to consult properly ahead of his nomination of Ngcobo.

The opposition urged Zuma to restart the process from scratch saying they would prefer current Deputy Chief Justice Dikgang Moseneke for the post.

Zuma wrote a formal letter to the parties saying that Ngcobo remained his preferred candidate, though he had not "taken a final decision on whom to appoint". He urged them to comment on his nomination and put forward their case for Moseneke.

But the parties remained unmoved. They said his remarks had side-stepped debate on the real issues at stake.

The opposition said Moseneke was the best qualified person for the post because he had been working with Langa for the past four years. They argue Moseneke has been passed up for promotion because he angered the ANC in stating, before the ruling party's Polokwane national conference -- where Zuma won control of the ANC -- that the future of the country did not lie with delegates, but with the electorate.

The announcement would be made at the Presidential Guesthouse in Pretoria at 3pm