Two dozen campaigners, some wearing gasmasks and most carrying placards, gathered outside one of the plant's entrances to voice opposition to the company's proposal to burn used tyres, recycled oil and carbon dust in kiln six following the completion of a $75 million upgrade.

Bundanoon environmentalist Peter Lach-Newinsky - one of many who have drafted a submission to the Department of Infrastructure, Planning and Natural Resources (DIPNR) in objection to the scheme - dressed as the Grim Reaper to make clear his opinion about the effect of the intended waste incineration.

One poster held high among the throng of demonstrators questioned whether the move was a waste solution or toxic pollution. Others called for public disclosure and for Blue Circle to "come clean".

The anti-incinerator group stood for an hour waiting for an opportunity to speak to Mr Unsworth, who eventually appeared to declare he was available mid-afternoon to listen to their concerns.

The protesters argued that they wanted a proper public meeting - with notice to enable all interested parties the opportunity to attend - and it was agreed that such a forum would take place at Wingecarribee Shire Council's Civic Centre at 7pm on Thursday next week.

Mr Unsworth later told the News the demonstrators' wait for his arrival was due to the fact he was halfway through an inspection of the ongoing upgrade when he received their request for his presence.

"There was no warning that such a discussion was required," he said, adding that Blue Circle had always been willing to participate in a public meeting.

Cr Larry Whipper, who was among the protesters yesterday, suggested Blue Circle's application should not be determined until after the completion of a national study into the impact of the accumulation effect of burning waste products later this year.

"The precautionary approach needs to be taken," he said.

"One thing about air is we all share it, we all breathe it. We have to look after it."

Greens spokesman Jim Clark said a threefold increase in dioxin emissions from the plant was "a real concern" and Mr Lach-Newinsky described it as "spreading the problem over the countryside".

Friday is the official deadline for public comment on Blue Circle's application - two extensions having been granted already - however given the public meeting will not be held until next week it is understood that late submissions will still be considered by DIPNR.