The SABC has rejected "with contempt" a claim that it sabotaged the sound during Saturday's marathon live broadcast of Jacob Zuma's first public policy speech as ANC president.

The ANC Youth League said on Sunday that the public broadcaster tampered with the audio during Zuma's address at the party's 96th anniversary rally in Atteridgeville.

This comes after most of the broadcast, on radio and television, was marred by badly distorted sound.

"We call on the SABC to accept the fact that its agenda was defeated in Polokwane, and it should adapt and accept that there is new leadership in the ANC or face the consequence of its actions. No amount of sabotage will ever move this reality," the league said.

However, SABC spokesperson Kaizer Kganyago said the league's claim was completely unfounded.

"We reject with contempt the allegations that we deliberately tampered with the audio during the address of the ANC president and that we sabotaged our own broadcast," Kganyago said.

Group chief executive Dali Mpofu was personally looking into the matter.

Preliminary findings were that there had been a problem with the cabling that led to the public address system from which the SABC was initially forced to take its audio feed.

"The SABC was prevented from putting its microphones on the podium, as is procedure in all broadcasts of this nature," Kganyago added.

Only about 35 minutes into Zuma's speech were technicians permitted to move the microphones to the podium.

The SABC apologised to listeners and viewers for the problems, Kganyago said.

He also said the league should have investigated the matter, and familiarised itself with the broadcasting environment, before making such unfounded allegations.

The SABC has previously been accused by the league of being biased towards President Thabo Mbeki, Zuma's beaten rival in last month's contest for the ANC presidency. - Sapa