The details of the electronic toll collection contract (ETC) should not be kept confidential, the Opposition to Urban Tolling Alliance (Outa) said on Monday.

"It shouldn't be confidential. It is taxpayers' money that is being used to pay the tolls, so the taxpayer should know what the money is being used for," said Outa chairperson Wayne Duvenage.

However, there was nothing he could do about it after Outa agreed to sign a confidentiality agreement, said Duvenage.

This was the only way Outa was able to get access to the ETC contract to prepare for its court case.

Outa said in a statement later on Monday there was a misunderstanding over its decision to sign the agreement.

"This matter certainly is not a case of Outa 'doing a deal with the enemy', but rather, a case of acting in the best interests to protect the judicial review dates," it said in a statement.

The organisation was responding to a report in The Star newspaper on Monday that parts of the high court review of the project in November could be held in camera because of the confidentiality agreement.

This meant that taxpayers might never know the full agreements, pricing, and subcontracts surrounding e-tolling.

Last month, the Constitutional Court overturned an interim order which put a hold on the Gauteng e-tolling project.

During the case, the legal team representing the South African National Roads Agency Limited (Sanral) made selective references to the ETC contract, which Outa had not seen.

"Now imagine a court case for them to use the contract even though we had not seen it," said Duvenage.

"We needed to see them... so we were asked to sign a confidentiality agreement to see it."

The Democratic Alliance said the signing of the confidentiality agreement was suspicious.

"We have to ask why does Sanral appear to be hiding something, and who is it seeking to protect?" DA MPL Neil Campbell asked in a statement.

He said full disclosure had to be given to Gauteng residents.

"This case should take place with unrestricted public access, despite indications that Sanral wants part of it to be held behind closed doors," said Campbell.

"Anything less than full disclosure will confirm that Sanral and the government have something to hide."

He said Parliament, on request, received 27 of the 33 contracts relating to the e-tolls. The others were not given.

"Why are the other six contracts not forthcoming?" he asked.

"The latest in the smoke and mirrors saga is the confidentiality requirement which adds to the thick veil of secrecy surrounding e-tolling."

This added to speculation that someone at Sanral or in government stood to make "a pot of money" from e-tolling, said Campbell.

The Constitutional Court found that the High Court in Pretoria had not considered the separation of powers between the high court and the executive.

In April, the high court granted Outa an interdict, ruling that a full review needed to be carried out before electronic tolling could be put into effect.

The interdict prevented Sanral from levying or collecting e-tolls pending the outcome of the review.

Sanral and the National Treasury appealed against the court order, and said delays prevented the payment of the R21-billion incurred in the project's building costs.

The review was expected take place in the High Court in Pretoria on November 26.