Southern Cape landowners and environmentalists are "frustrated" by the lack of answers to their questions about proposed prospecting and drilling for gas and oil in the region, says the Wildlife and Environment Society of SA (Wessa).

But the consultants running the statutory public participation process about the project say that, while they appreciate the frustrations, they also believe that these groups now understand why specific answers can't be provided.

This is because until gas or oil is actually located in geological deposits it is not possible to predict what the environmental impacts of exploration boreholes drilled to test their viability might be.

And they say that a further public participation process will be required before any viable gas or oil deposits can be commercially exploited.

This emerged on Tuesday from the first of four "open days" being held to discuss draft environmental management plans for oil and gas exploration rights, granted by the Petroleum Agency, South Africa to Pretoria-based exploration company Advasol for nine sites in the southern Cape.

These sites comprise numerous farms and offshore areas in the Struisbaai, De Hoop, Cape Infanta, Stilbaai and Mossel Bay districts.

Exploration rights will only be finally confirmed once separate environmental management plans have been approved for each site.

Among concerns expressed are the possible effect on southern right whales and on other aspects of the marine environment. However, the exploration company has been at pains to stress that no drilling will be done at sea.

Tuesday's open day at the Mowbray Presbyterian Church, where 47 "interested and affected parties" signed the register, was part of this environmental approval process. Further open days are being held in Bredasdorp, Witsand and Albertinia.

Wessa senior environmentalist Philippa Huntly, who attended on Tuesday, said there had been "a lot of frustration expressed" by those present.

"And rightly so, because of the general responses from Advasol to specific questions about the prospecting process. And they were also unable to answer many questions, so it (the open day) hasn't really worked out well. It just seemed inadequate."

But consultant Erika du Plessis said the open house had been designed to talk to small groups of one-to-three people at a time in front of a map or poster depicting all the issues raised at the meeting.

"But participants insisted on a question-and-answer session and did not read the information on the posters up front. This caused a lot of questions to be asked that would have been clarified if people had gone through the displays first.

"The project team had not prepared for (such) a session and did come across as unable to answer, but this was merely because the format of the meeting.

"After the impromptu Q-and-A session, small groups formed spontaneously between stakeholders and members of the team and a great number of issues were clarified."