The African National Congress Youth League (ANCYL) believes it knows why South African Communist Party (SACP) delegates booed their leader, Julius Malema, last week - it is all linked to the 2012 succession debate within the ruling party.

But, the youth league vowed, the booing incident will turn out to be a "long-lasting lesson" to the SACP and its deputy general secretary, Jeremy Cronin.

The ANCYL released a statement on Monday in response to the booing of Malema at a conference in Polokwane last week.

"The [ANCYL] NWC [national working committee] is convinced that the main reason why the SACP leadership supports the booing of the ANCYL president is because they believe the ANCYL does not support the bid of Blade Nzimande to become deputy president of the ANC in 2012, and that the Youth League will not support Gwede Mantashe for second term as ANC secretary-general," the ANCYL said.

"The ANCYL will not agree to the dumping of undemocratic leaders into the ANC, and we will decide on the leadership of the ANC when the time is right."

The ANCYL also blamed Mantashe, who is also chairperson of the SACP, for the ruling party's silence "on the behaviour of delegates at the Communist Party congress".

"The ANC is silent because Mantashe is conflicted and does not want to speak against the SACP, where he is a chairperson.

"The ANCYL NWC is of a view that the booing of the ANCYL president by some delegates in congress was planned by the leadership of the Communist Party."

These apparently included Nzimande, who is the general secretary of the SACP and current Higher Education Minister, Cronin and Young Communist League leader Buti Manamela.

"The reason why the leadership of the Communist Party did not condemn the behaviour of delegates attests to the fact that the SACP leadership agrees with the booing.

"The SACP leadership further sang along to insulting songs that [were] sung in the special congress about the leadership of the ANCYL, and did not condemn delegates who were doing so," said the ANCYL.

The statement accused Nzimande of being a "master character assassinator" who was trying to assassinate Malema's character.

Turning to Cronin, who has had a public spat with Malema over the nationalisation of mines, the ANCYL said he suffered from a "superiority complex".

"Jeremy Cronin's statements that the booing was a lesson to the president of the ANCYL will be met with practical action on the ground and will be a long-lasting lesson to him."

Also, Cronin was too lazy "to engage on deeper ideological questions", said the ANCYL.

"He continues to oppose the nationalisation of mines despite the fact that the special congress resolved on nationalisation of mines, and our conclusion is that he is protecting the interests of white monopoly capital."

Lastly, the ANCYL statement describes Manamela as a "factionalist" and a "product of undemocratic practices and processes in the Communist Party".

"Members of the ANC and ANCYL are called upon to rise and defend the African National Congress against the pressure group and factionalists masquerading as Communists," said the ANCYL.

"Any attempts to liquidate the ANC will be defeated."