It is in the interests of all South Africans that they be counted in Census 2011, Minister in the Presidency Trevor Manuel said on Monday.

Speaking in the National Assembly, 20 days before the big count starts on October 10, he told MPs the greatest risk was people who did not want to take part.

"Perhaps the greatest risk is that people do not voluntarily participate in being counted -- they shut the doors, let out the dogs and turn out the lights when the enumerators approach."

Apart from the fact that participation in the census was a statutory obligation, it was "directly and unashamedly" in people's own best interests.

Gathering accurate information from residents of South Africa's estimated 14.5 million households was essential for government to provide adequate and effective services.

"Good workers, such as we aim to be in the service of our people, need the best and sharpest tools, and there is simply no other way to acquire this than through conducting a detailed census," Manuel said.

The last census was conducted in 2001, with an undercount of 17 percent.

The large undercount was attributed to enumerators having difficulty gaining access to the high-walled homes of the wealthy.

There were also problems counting people in informal settlements.

Census 2011 will involve 156,000 enumerators, co-ordinators and supervisors. Manuel said Statistics SA had completed all the necessary preparations.

"Field workers have gone out, armed with clipboards, to list every dwelling in the country; questionnaires have been prepared, printed and distributed along with other census materials; 130 offices have been rented and equipped; 6000 vehicles hired; advertisements have been placed; and pilots and dress rehearsals have been conducted.

"The preparations completed speak to the scale of the operation -- the largest deployment of people in peacetime in our country," he said.

In terms of Section 16 of the 1999 Statistics Act, when it comes to a census, "every person... must to the best of his or her... knowledge and belief, and subject to the right to dignity and privacy, answer, when so required, all questions put orally or in writing... ".

According to the act, anyone refusing to answer a question, or who knowingly provides a false or misleading answer, could, if convicted, be liable to a fine of up to R10,000 or six months imprisonment, or both.

Opposition parties in the House on Tuesday pledged their support for the census.

Results of the census are expected in November next year. According to Statistics SA, the exercise will cost R3 billion.