The SABC board has vowed to investigate allegations that the broadcaster's acting head of news, Phil Molefe, has banned staff at the national broadcaster from interviewing former president Thabo Mbeki.

The Sunday Timesreported yesterday that Molefe ordered news executives to stop interviewing Mbeki on all SABC radio stations and television channels.

It is believed that Molefe's decision was sparked by an interview the broadcaster had with Mbeki after Ghana's World Cup quarterfinal victory over the US.

During the interview, Mbeki congratulated Ghana on their performance in the soccer tournament, and called on the people of Africa to rally behind the West African nation.

Molefe, reportedly on instruction from ANC headquarters, Luthuli House, told senior news executives that Mbeki's appearance on SABC channels ''undermined" his successor, President Jacob Zuma.

SABC board chairman Ben Ngubane said: "I will find out what is happening. It's not editorial policy to do such things. He [Molefe] hasn't told me that."

A senior SABC executive, who spoke on condition of anonymity, yesterday told The Times that there was no truth in reports that Molefe ''banned" Mbeki from being interviewed.

The executive said the issue cropped up when a journalist suggested that he be interviewed in connection with the conviction of Jackie Selebi, the former national commissioner of police and former head of Interpol.

The executive said that Molefe "addressed senior news executives saying, 'Guys, you need to know when to interview people'."

Molefe reportedly said: "You must know when to talk to him [Mbeki]. You can talk to him about other issues, like service delivery, but not this. There is a current administration; why not talk to them about Selebi."

This did not amount to gagging the former president, the executive said, adding that the SABC had no reason to gag him.

DA chief whip Ian Davidson said the party will ask Molefe to appear before the parliamentary portfolio committee on communications to explain the "disturbing and scandalous" reports that he had banned Mbeki from SABC television and radio channels, on instruction from Luthuli House.

"This amounts to a full-on assault on the rights of South Africans to receive impartial, balanced news from the state broadcaster. It is simply unconscionable that any political party would be dictating editorial policy to the SABC," said Davidson.

The SABC denied the allegation made in the Sunday Times article, in a strongly worded statement issued by spokesman Kaizer Kganyago.

''The article ... is totally false, malicious and intended to mislead . and without basis," Kganyago said.

". There was never any instruction given to anybody, or any intention to ban former president Mbeki from any of our platforms."