The Witness newspaper on Thursday said it would not hand over the details of a motorist who used his cell phone to provide the newspaper with video footage of KwaZulu-Natal Premier Sbu Ndebele's convoy doing 160 kilometres an hour.
Witness deputy editor Yves Vanderhaeghen said: "We have spoken to our lawyers. Our lawyers have advised them that we cannot do this. And we said so before."
He said the MEC "would have to find other ways" to find the motorist.
Vanderhaeghen was speaking after KwaZulu-Natal Transport MEC Bheki Cele told the KwaZulu-Natal legislature that the motorist would be arrested for breaking the law.
The SABC quoted him as saying vehicles transporting VIPs were allowed to use blue lights and were driven by police officers.
The MEC could not be reached on Thursday afternoon as he was addressing the legislature on safety and security - his other portfolio.
Transport spokesperson Nonkululeko Mbatha could not say whether the speed limit applied to VIP convoys.
Earlier in the week the SA National Editors' Forum condemned a demand by the department that The Witness newspaper in Pietermaritzburg supply the motorist's name.
The motorist said he had been forced out of the fast lane by the premier's convoy and had been so angered that he had given chase, capturing evidence of the alleged misconduct on his cellphone's camera.
The pictures showed the convoy's cars straddling traffic lanes and speeding - indication of the speed was shown in a photograph taken of his own car's speedometer as the motorist pursued the convoy - and were published on April 14.
The Witness has now received a letter from the provincial transport department's attorneys demanding to know the identity of the motorist "who provided video footage of Premier Ndebele's convoy".
The Witness has refused to hand over the motorist's details to the department on the grounds that to do so would contravene a journalist's code of ethics, which guarantees the protection of a newspaper's sources when information has been supplied in confidence.
Ministerial convoys have raised the ire of numerous motorists.
Last week the Daily News reported that the convoy of ANC deputy president Jacob Zuma had muscled motorists off the N3 and that one of his security guards allegedly pointed a rifle at one motorist who would not give way to them.
Public Works MEC Lydia Johnson escaped injury when her convoy was involved in a vehicle pile-up near the Pavilion Shopping Centre in February while rushing to Pietermaritzburg to attend Ndebele's State of the Province Address.