CBC News has uncovered additional information about the meeting in which Prime Minister Stephen Harper bluntly told Senator Mike Duffy he would need to repay expenses that are the heart of an ongoing scandal in the Senate.

Multiple sources have provided details of that exchange and an earlier meeting between Duffy and Nigel Wright, Harper's former chief of staff, who resigned after it was revealed he had given a personal cheque for $90,000 to the embattled senator to cover those expenses.

Harper has consistently denied that he knew anything about the arrangement. 

Wright met with Duffy on Feb. 11 across from Parliament Hill in the Langevin Block, in a room near the prime minister's office, and told him that despite previous assurances that his expenses were legitimate, he would have to pay back the money.

Duffy protested, arguing that he had done nothing wrong and asking to have a meeting with Harper. According to multiple sources, Wright said he'd arrange a meeting in 48 hours. 

Two days later at a Conservative caucus meeting in the Centre Block of Parliament, half a dozen MPs, including Dean Del Mastro, Pierre Poilievre and Mark Warawa, voiced their support for Duffy, saying he had been smeared by media reports and the party should stand behind him.

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Half a dozen Conservative MPs spoke up in defence of Senator Mike Duffy during a caucus meeting in February, CBC News has learned. (Sean Kilpatrick/Canadian Press)

Harper, however, was adamant that anyone with improper expenses should either pay them back or leave. 

After the meeting had ended, Harper, Duffy and Wright stayed behind and talked further with only security and logistic personnel present.

Duffy again made the argument that his expenses were legitimate. Harper said it wasn't about right or wrong but rather about perception, multiple sources say. The public wasn't buying explanations and Duffy had to pay the money back, Harper told him.

Harper has denied saying this, but has said he ordered Duffy to pay back ineligible expenses. 

There was no discussion about where the money would come from, one source told CBC News, and the meeting ended with Harper saying Wright would make the arrangements.

The Prime Minister's Office has called the comment about the arrangements "categorically false."

The meeting lasted less than five minutes. Harper and Duffy haven't spoken since, CBC News has learned.

Watch the complete report from CBC News' chief correspondent, Peter Mansbridge, above.