Thor Chemicals has agreed to pay R24-million towards cleaning up toxic mercury waste at its factory outside Durban, according to deputy environment minister Rejoice Mabudafhasi.

She made the announcement at a public meeting in Durban this week. The figure of R24-million was for the first phase of the clean-up, which involves treating, removing or destroying up to 8 000 tons of mercury-contaminated sludge.

She did not elaborate on the schedule for and methods or eventual costs of cleaning up sludge now stored in warehouses and waste ponds near Cato Ridge.

Earlier this year, however, Mabudafhasi spoke of a total clean-up bill of R60-million when she paid a visit to the Thor factory in Cato Ridge and the legal offices of Guernica Chemi-cals, which took over the running of the factory in 1999.

Guernica Chemi-cals' legal representative, Roy Monk, said on Wednesday that he was not at liberty to comment on the progress of discussions with the government, but said he was confident that "some progress is being made".

Buti Mathebula, director of chemicals and hazardous waste management in the department of environmental affairs, said he could not elaborate as he had been out of the country for two weeks.

But he said hazardous waste experts had been invited to visit the Thor factory on Friday to design tender documents for the clean-up.

Thor hit the headlines in the late 1980s and early 1990s after environmental group Earthlife Africa picked up reports of workers "going mad" at the chemical and mercury plant. Mercury was also found in a river 15km downstream from the plant.

At least four workers died after allegedly being exposed to massive quantities of mercury at the British-owned factory.

Local factory managers were arrested and charged with culpable homicide but charges were dropped later for lack of evidence and the company was fined R13 500 for contraventions of labour and safety laws.

Later, following legal action in the British courts in 1997 and 2000, Thor's London-based parent company agreed to pay out-of-court settlements of R12-million to 38 workers or their families.

Thor also shut down mercury operations and a commission of inquiry recommended the destruction of a massive stockpile of mercury-contaminated waste stored at the factory.

Government officials say there is evidence that some of the stock-piled waste has started to leak out into soil or groundwater.

Four months ago, Mabudafhasi flexed new anti-pollution muscles by serving a clean-up notice on the company in terms of the National Environmental Management Act of 1998.

It remains unclear whether the waste will be burned in an incinerator, dumped in a hazardous-waste landfill site or shipped back to the countries that generated some of the mercury waste.