ANC president Jacob Zuma's lawyers expect to file papers in the Constitutional Court later on Monday asking for permission to challenge a Supreme Court of Appeal ruling, his lawyer said.

The ruling allowed the state to reinstate the corruption charges against him.

"It should be done this afternoon," said Michael Hulley.

A court official said the deadline for filing is 3.30pm on Monday.

The application for leave to appeal the January judgment forms part of the broader legal strategy his lawyers are putting in place to free him of the almost 10-year-long matter.

On Wednesday, the National Prosecuting Authority would square up to Zuma's and arms company Thint's lawyers as they appear in the Pietermaritzburg High Court to have the corruption charges placed back on the court roll.

NPA spokesman Tlali Tlali said that the effect of the SCA ruling was to reactivate or lift the freeze on the criminal case against the parties.

Arms company Thint had also been resummonsed and their legal representatives were also expected in court on Wednesday.

There had been no change to the charges Zuma and the Thint companies would face. These included racketeering, corruption and money laundering in a case related to allegations of impropriety in an arms deal.

The SCA judgment questioned many aspects of the finding of
Pietermaritzburg High Court judge Chris Nicholson, which set aside the prosecution against Zuma and Thint while it was still in the early stages of a second attempt at bringing the case to trial.

In January the SCA wrote that Nicholson had adjudicated on matters not brought before him and upheld the NPA's appeal.

The ANC in KwaZulu-Natal said about 15,000 people would descend on Pietermaritzburg to support the man the ruling party had endorsed to become the next president.

A night vigil on the eve of the appearance and a mass rally to punt the party's manifesto were planned, along with 500 marshalls to keep the crowds in check, said provincial secretary Senzo Mchunu.

"We have been provided with a perfect opportunity and platform to campaign and we use it as such," he said.

"The ANC calls on ANC members and supporters to continue demonstrating their full support for the ANC president by being at the trial," said spokesman Carl Niehaus.

The police said they and the city were ready for the day and the inevitable road closures.

Senior Superintendent Henry Budhram said they appreciated the levels of support and co-operation they had previously received from people at Zuma's appearances, and hoped for the same on Wednesday.