Sanral is misleading the public by saying the failure to pay toll fees is against the law, regardless whether an invoice is issued or not, Justice Project SA (JPSA) said on Monday.

JPSA was responding to a statement the SA National Roads Agency Limited (Sanral) made on Sunday.

"Not paying your toll fees is not just a traffic offence, but a criminal one," Sanral spokesperson Vusi Mona said in a statement at the time.

"The legal obligation to pay toll arises from using the toll road and passing underneath a gantry, not from an invoice that is forwarded to the road user."

JPSA chairperson, Howard Dembovsky, said regulations were very clear on the matter of invoices.

"It says that Sanral must issue an invoice to any person from whom it requires payment of outstanding e-tolls.

"The word 'must' in legislation... is a prescriptive word which places a duty on the party against whom it is applied," he said.

Dembovsky said the Administrative Adjudication of Road Traffic Offences (AARTO) Act decriminalised road traffic offences including non-payment of tolls.

He said AARTO made provision under charge codes 3820 and 3821 under Schedule 3 of the Act to deal with those matters.

"Therefore if AARTO is applied to speed fines on the respective freeways then [it] applies to all minor infringements such as non-payment of toll fees," he said.

The transport department should be aware that AARTO specifically decriminalised traffic violations and no one could be guilty of a criminal offence for non-payment as Sanral claimed.

"JPSA... will not relent in exposing both Sanral's incompetent handling of the e-tolling issue, and Vusi Mona's constant misleading threats against the public."

Mona said on Sunday that all the signs posted along the tolled roads indicated that payment had to be made within seven days.

"Sanral is using legally available resources at its disposal to contact vehicle owners. We are issuing notices, with invoices to follow, in order to alert road users that they have outstanding debt."

Mona could not be immediately reached for comment on Monday.