Photographs of Springbok players huddled naked up to their waists in a lake rocked South African rugby on Friday, piling pressure on coach Rudolph Straeuli to quit after his team's World Cup quarter-final exit.

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The Johannesburg Star gave over half its front page to a photograph of at least 10 naked Springbok players packed tightly together, apparently exhausted and freezing, holding rugby balls or billy cans to preserve their modesty.

The paper said the picture was taken during the Springboks' pre-World Cup team-building camp in the bush two hours drive north of Pretoria, where players underwent gruelling ordeals intended to build mental strength.

After returning from their quarter-final defeat by New Zealand at the World Cup in Australia this month, the team faces a possible government inquiry into allegations of racism among players almost a decade after South Africa abandoned apartheid and white minority rule.

Straeuli's methods have been severely criticised and revelations of a programme closer to a boot camp for elite military recruits than a sports training camp have increased the pressure on him.

"We have no comment at this stage," a spokesman for SA Rugby told Reuters.

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The Sunday Times had reported last weekend that the controversial camp was designed by the team's security consultant, Adriaan Heijns, a former South African police special services operative.

The report claimed that naked players were crammed into foxholes and doused repeatedly with ice-cold water while the English national anthem and New Zealand's pre-match haka were played over and over again.

They were also forced into a freezing lake in the early hours of the morning to pump up rugby balls under water. When some of the players tried to get out they were ordered back into the water at gunpoint, The Sunday Times said.

Team manager Gideon Sam denied on Thursday that any of the training had been carried out at gunpoint, or that players were forced to crawl naked through the bush.

"Sure, the guys were pushed hard, but that is what preparing for battle is about," he said on the team's Web site.