OTTAWA - The Prime Minister's Office has "categorically'' denied that any Conservatives offered a dying MP a lucrative life-insurance policy in exchange for his support on the eve of a critical Commons vote.

Stephen Harper's communications director sent The Canadian Press a brief e-mail Wednesday rejecting allegations the party offered Chuck Cadman the million-dollar policy.

"Yes, I categorically deny it,'' wrote Sandra Buckler.

It was the first time the government explicitly denied the allegation since the story broke last week.

Buckler's reply came after nearly a week of repeated questions to the PMO and a party spokesman about the alleged life-insurance offer.

Wednesday also marked the first time the Tories explicitly said in the House of Commons that no one from the party offered the ailing Cadman life insurance.

"There was, in fact, no life-insurance policy proposal that was made,'' said Tory MP James Moore.

"There were no discussions about a million-dollar bribe.''

Before Wednesday, the Conservatives' response had been that the only offer made to the Independent MP was an invitation to rejoin his former party.

But party spokesman Ryan Sparrow told The Canadian Press earlier this week that two close confidants of then-Opposition leader Harper offered a repayable loan to Cadman's local riding association to cover campaign expenses if he rejoined the party.

It's still not clear how much Doug Finley and Tom Flanagan offered to loan the riding association, or what the terms of repayment were. Elections Canada has said the maximum riding spending limit for election expenses in Surrey North during the last campaign was $73,788.30.

But in biographer Tom Zytaruk's coming book, Cadman's widow says two Tory operatives made the offer of life insurance on the eve of the vote which could have brought down Paul Martin's Liberal minority government.

Dona Cadman -- the Tory candidate in her husband's former B.C. riding -- later said she considered it a bribe. Two other family members have corroborated her story.

She maintained in a statement released Monday that party officials made the offer, which she chalked up to "the overzealous indiscretion of a couple of individuals.''

But she said Harper convinced her more than two years ago that he knew nothing about an alleged offer.

A leaked version of the manuscript of Like A Rock: The Chuck Cadman Story, said the alleged offer was made on May 17, 2005 _ two days before the historic confidence vote in which the Liberal government's fate rested on the shoulders of the ailing MP.

But the Conservatives maintain that Flanagan and Finley met with Cadman only once -- on May 19, 2005.

The publisher has since removed the contested date from the final version of a book.

Harbour Publishing struck the May 17 reference from the book after Cadman's former legislative assistant, Dan Wallace, called the date "inaccurate'' in a statement, publisher Howard White said.

He added that no political parties called him or otherwise influenced the decision.

At the centre of the controversy is a tape that surfaced last week suggesting Harper not only knew an offer of "financial considerations'' was allegedly made to Cadman, but also gave it his blessing.

During the September 2005 interview with Zytaruk, Harper said he cautioned the two that their efforts would be was fruitless.

The prime minister has yet to explain what he meant by "financial considerations.''

Cadman died of cancer two months after voting to keep the Martin government alive for a few more months.

The Liberals have asked the RCMP to investigate the matter, and all three opposition parties had initially wanted the Commons ethics committee to look into it.

But New Democrat MP Pat Martin says he'll block any motion for the ethics committee to probe the alleged affair. The New Democrats say the matter would be better looked into by a special federal prosecutor.

Meanwhile, Liberal MP Paul Szabo said Wednesday he doesn't want to launch an ethics committee probe into the Cadman affair.

If it did, he said the extra workload would mean the committee would end up delaying its report into the Mulroney-Schreiber affair which, in turn, would delay the start of a public inquiry into that matter.

In any event, Szabo -- the ethics committee chair -- said that since the Cadman affairs involves possible Criminal Code violations, it would be more appropriate for the justice committee to probe the controversy.

"I view that the justice committee is a preferable standing committee to address this matter,'' he said.

Meanwhile, Harper served notice of intent Monday to sue top Liberals over their comments about the purported incident -- the first time a sitting prime minister has sued the opposition for libel.

Liberal Leader Stephane Dion, the Liberal Party of Canada and MPs Ralph Goodale and Michael Ignatieff were all served letters over statements published on the party's website.