Nelson Mandela yesterday delivered his toughest speech since his release from prison 15 months ago, warning the government that violence would spill over to the white areas unless drastic moves were made to stop the carnage.

Mandela was speaking on the eve of a crucial African National Congress National Executive Committee meeting to consider the government's response to the ANC's ultimatum on violence, with talks between the two groups balanced on a knife edge. In an angry off-the-cuff speech at a commemorative service in Kagiso, the scene of a massacre of 28 people on Sunday by Inkatha-supporting hostel-dwellers, Mandela warned there would be no negotiations unless the government banned the carrying of spears and sticks -- and said he had been unable to move President FW de Klerk on this issue.

The ANC deputy president accused De Klerk of racism, said Inkatha wanted to "rise to power on the corpses of dead people" and blamed the government and security forces for actively promoting anti-ANC violence. Addressing a commemorative service at the Kagiso Hall for the 28 people murdered at the Swanieville squatter camp, Mandela warned the government that the violence would spill into the white areas, and that white civilians would be hit unless drastic moves were made to stop the carnage. He warned the community against taking such action.

Addressing the issue of the ANC's ultimatum for the banning of spears, Mandela said the ANC was "putting tremendous pressure on the government" adding that there was "no question of negotiations in this country" unless De Klerk conceded. He repeated this point several times, but noted that "I was not able to move Mr De Klerk because like all average whites he has no regard for the black man's life".

He said De Klerk told him that if the government found that there was abuse of spears and sticks he would take action. 'I told him that over 8 000 blacks had died in the violence since 1984, and that these spears are being abused now. How many more people should die before you ban these dangerous weapons?"

He added that "if only 50 whites had been killed there ere would have been a revolution in this country" and the government would have banned all weapons immediately. "But because it is blacks, we have to work for years to convince him that he needs to protect the lives of our people and for spears to be banned."

Referring to Inkatha as "an organisation with no membership in the Transvaal he said they were unable to get members by "appealing to the people to join them" and therefore were using force for this end. "They want to rise to power on the corpses of dead people." He added that Inkatha had a habit of bussing people to rallies in areas where they didn't have a "single member".

Dismissing police claims that they had been unaware of Inkatha plans for Sunday's massacre, he said the police had spies in every hostel, and if hostel dwellers "decide to attack tomorrow, the police will know immediately. "It is therefore not true when they say that they were not aware of what was happening when the hostel attacked."

Mandela said these massacres were happening because "it has become the policy of the government to allow this in order to weaken the liberation movement". He warned that when people realised "the government is working with the black organisation which is killing our people", they would move into the white areas and kill innocent people.

"The liberation movements will not support it because there are many innocent people there who have nothing to do with the violence. There are many whites who value the lives of our people, and in any attack both innocent and guilty will be killed ... We don't want you to do that." He added the government was making a mistake because one effect of its support for violence was to help forge unity between the ANC, Pan Africanist Congress and the Azanian People's Organisation.

He firmly embraced these organisations, referring to the unity which had been forged between them on Robben Island. "By killing so many innocent people they have succeeded in bringing us together." Yesterday's service was co-hosted by the three organisations and addressed by Dikgang Moseneke of the PAC and Pandelani Nefolovhode of Azapo, as well as by SACP general secretary Joe Slovo and Umkhonto weSizwe's Chris Hani. Outside the, hall about 15 000 people gathered, many toyi toying, and some armed with "traditional weapons".