MONTREAL -- A witness who has delivered bombshell testimony at Quebec's corruption inquiry detailing decades political graft admitted Monday a part of his testimony was a lie.

Gilles Cloutier returned to Quebec's corruption inquiry with a message: that although he had testified that he was the owner of a home in Quebec's Charlevoix region he was, in fact, renting it.

It was the first thing the former political organizer discussed upon the inquiry's return from a one-week break. Cloutier admitted he lied about owning the house where public servants were entertained by Roche, an engineering firm.

A clearly embarrassed Cloutier, 73, said Monday that he was "saddened" and felt "a lot of guilt" about lying to the inquiry. While investigators came to see him about the discrepancy last week, Cloutier said he was ready to set the record straight even if he hadn't been approached.

Cloutier had always told those close to him that he owned the house.

"I did it out of pride. I told everyone that I was the owner when I was not," Cloutier said on Monday.

He had made waves at the inquiry with an insider's account of how the construction industry used its political connections to manipulate the procurement process, and even rig municipal elections.

Some of his testimony had been embarrassing for the Parti Quebecois. A lawyer representing the Parti Quebecois seized on Monday's admission to launch a sustained attack on Cloutier's credibility.

Estelle Tremblay noted that Cloutier not only lied about owning the home, but also about fictitious real-estate transactions involving the property.

Tremblay pointed out that Cloutier had told the inquiry that he'd purchased the home for $200,000 with his own money and subsequently resold it for $400,000 -- all lies, Cloutier was forced to admit.

"Do you realize you perjured yourself?" Tremblay asked Cloutier in a tense exchange.

"Maybe not perjury," he said, fumbling for an explanation.

"I lied," he added.

But he insisted the rest of his testimony was true.

"I have reviewed all my testimony . . . and everything I said is true and I swear it," Cloutier said.

Tremblay wondered what else Cloutier may have gotten wrong in his previous testimony -- asking him specifically about a fundraiser he allegedly organized in 2001 for a PQ candidate where 15 executives paid $1,000 a head for a chance to chat with then-transport minister Guy Chevrette.

Tremblay noted that nowhere in the PQ's accounting for that year was there any indication such an event had taken place.

Under fire, Cloutier insisted the rest of his testimony had been accurate, including details of that fundraiser at a Best Western hotel in St-Jerome, north of Montreal.

Tremblay wondered if Cloutier, suffering from an unspecified illness and requiring medication, might be having memory problems. But the witness insisted his memory was good.

"I am very sick, but it does not affect my memory," he said.

Tremblay also quizzed Cloutier about his account of a $100,000 payment to a friend of Chevrette's for access to the minister.

Cloutier had said that after the payment was made to the friend, he got help winning a lucrative public-works contract -- and he stuck to that story Monday.

Lawyers for Chevrette and the friend, Gilles Beaulieu, are asking the inquiry for the right to cross-examine Cloutier too.

Cloutier is not the first high-profile witness to recant details from his testimony.

Martin Dumont, whose testimony helped bring down the mayor of Montreal, has also admitted to making up an anecdote. But, as with Cloutier, he is sticking to the rest of his story.

This Cloutier testimony had damaged a number of reputations -- including that of a PQ stalwart, Chevrette, and also a sitting judge.

Cloutier was a former political organizer who worked in business development for major Quebec engineering firms Roche and Dessau.

The corruption inquiry is expected to turn its attention to Laval with the following witnesses this week.