It involved a petrol station carpark, a fistful of cash and a red-eyed apology.

The elusive owner of an illegal housing set-up that burnt down in the inner city on Wednesday, almost killing 15 foreign students and workers, has finally surfaced to apologise to one of his tenants who lost her business.

Masaaki Imaeda, 64, previously boasted of running a $10 million set-up at the Alexandria industrial site, which contained four industrial units, self-storage for boats and min-vans and a squalid shanty town occupied by 15 Japanese, Korean and New Zealand nationals who were paying up to $160 a week to live in shipping containers, old buses and decrepit caravans stacked on top of each other.

Vicki Bonneville, whose catering business was destroyed by the fire, said she had been unable to get in touch with Mr Imaeda all week.

Fairfax's calls to Mr Imaeda also went unanswered and he wasn't home at his Alexandria or Kingsgrove apartments on Friday morning.

Ms Bonneville said she was finally able to meet with Mr Imaeda in the car park of an Alexandria petrol station on Thursday where he gave her $300 cash to refund her latest rent payment.

"He handed over some money and said, 'I'm sorry, I didn't mean for this to happen," Ms Bonneville said.

"I said, 'well that doesn’t help me, you’ve destroyed me, I don’t have any income, I don’t have any back up, I don’t have anything left'."

She said the property mogul, who owns at least five other properties across Sydney, was bleary and red-eyed and told her to speak with his solicitor when she demanded that he help offset the costs of re-establishing her business.

Fire investigators have revealed that the cause of the fire was most probably an electrical fault in a storage unit on the property.

Mr Imaeda did all his own electrical work, Ms Bonneville said. He had set up appliances and a port-a-loo in the carpark for the illegal residents to share. The property was uninsured.

Ms Bonneville complained to the City of Sydney council two months ago when he started illegally renting out the shipping containers, caravans and buses but it was never logged in the council's internal system so it was never investigated.

She will seek compensation from the City of Sydney, saying the fire never would have happened if investigators had visited two months ago when she complained.

Mr Imaeda is not facing criminal sanctions but could be fined or prosecuted by the City of Sydney. He has been issued with an order banning him from returning to the Alexandria site.

A Fire and Rescue NSW spokeswoman said on Friday that the fire was not being treated as suspicious.

"It is believed to have started in a storage shed," she said. "Given the extent of the damage and the building collapse, fire investigators have been unable to determine the exact cause of the fire however electrical fault is the most likely cause."