Preparations for the demolition of Eden Park's main stand have uncovered trap-doors hastily built to give the 1981 Springboks rugby team an escape route.

Heavy equipment was brought in at the Auckland ground to begin knocking down the South Stand as part of the redevelopment project for the 2011 Rugby World Cup.

The 1981 tour, which ended with the third and final Test at Eden Park, was marked by violent clashes between police and anti-apartheid protesters.

At the time, the only exit from the changing rooms in the South Stand was through the main doors and out on to the field.

Auckland builder Terry Henshaw was called in by Eden Park officials a few days before the Test to build a series of escape hatches.

He said he built a hatch up through the roof of the changing rooms and the floor of what became the cricket scorekeeper's box.

He also cut holes and built a series of interconnecting doors between offices and social areas.

"We didn't need to be sworn to secrecy," he said.

"It was just expected that we wouldn't talk to anyone who might be a protester."

A low-flying plane disrupted the Test by dropping flour bombs and play was also held up to remove flares lit by protesters.

However, security around the field was not breached and the South Africans did not have to use the escape hatches.

Rugby World Cup Minister Clayton Cosgrove, on site for the formal start of demolition, said the hatchways were a reminder of the park's importance to sporting and national history.

The "Flour Bomb Test", which the All Blacks narrowly won to secure a 2-1 series victory, was the last time the Springboks played in New Zealand until 1994.

Dismantling of the South Stand, which was opened in 1959, began on Sunday, the day after the All Blacks' 39-10 Tri-Nations victory over Australia.

Levelling of the stand is expected to take six weeks and up to 90 per cent of the wood, steel and concrete will be recycled.

The project will increase the park's capacity from 46,000 to 60,000.

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