South Africa’s top construction firms colluded over contracts to build and revamp stadiums for the 2010 World Cup, the Competition Commission said Wednesday, paving the way for possible prosecution.

The commission said dozens of firms “colluded” over the megaprojects, in some instances allocating tenders among the themselves and reaching deals “agreeing on profit margins.”

South Africa poured 20 billion rand (nearly $2 billion or 1.4 billion euros at today’s rates) into the construction and refurbishment of 10 stadiums to be used for the showpiece soccer tournament.

Five of the venues were built from scratch, including the 94,500-seater Soccer City in Soweto, which hosted the opening match and the final.

Twenty-one companies have admitted wrongdoing and have paid settlements totalling 1.4 billion rand.

But the commission said Murray & Roberts, Group Five, WBHO, Basil Read and Stefanutti Stocks have denied collusion.

Murray & Roberts have been granted leniency.

“They have denied collusive tendering, but we have evidence that they were involved in such behaviour,” said Mava Scott, the spokesman for the Competition Commission.

“We have now referred the matter to the Competition Tribunal for adjudication,” he said.

“They face collusion charges.”