MONTREAL -- A construction boss alleged to be close to the Mafia can't explain why his business more than quadrupled over a four-year span -- then dropped rapidly after a crackdown on corruption began.

Nicolo Milioto is testifying for a fourth day today before Quebec's corruption inquiry. The retired businessman has denied that he was in league with the Mafia or collected a tax on their behalf, and says his contacts with Mob figures were strictly social.

Today he is categorically denying the existence of any kind of cartel in the industry.

He was asked about the massive spike in his business between 2006 and 2009, which went from receiving $5 million in contracts a year to more than $20 million.

Milioto said the numbers are inaccurate and he offered to bring in his own books. He also could not explain, for a second day, why the majority of contractors in sewers and sidewalks all had ties to one small Sicilian town, Cattolica Eraclea.

He admitted to giving gifts to certain city employees, like bottles of wine or a meal a few times a year. In one instance, he laid concrete at the home of one city engineer.

But he said he never gave anyone cash and never expected any particular favours, except maybe quicker payments from the city.

"Nick Milioto has never given an envelope to anyone," he said.

Phone records were entered this week showing frequent phone calls between the construction boss, who retired in 2012, and competing company bosses.

Milioto said that he never colluded with other companies in his 23 years of owning his business.

"I'm giving you my truth, my version of the truth," Milioto said. "If there are others that are telling you the contracts were rigged I say, for my, part no."