A Conservative MP at the heart of a political ethics controversy says he secretly recorded conversations with high-ranking Liberals to show how low that party would sink.

But only Gurmant Grewal is speaking out about this: His party, which has told Grewal not to make some parts of the tapes public, hasn't said anything yet.

And the Conservatives haven't joined an NDP and Bloc Quebecois call for an RCMP investigation.

The Liberals deny making any offer.

The recorded conversations relate to discussions Grewal had with various Liberal politicians and officials about supporting the Liberal budget.

"I wanted Canadians to know how low this government can sink, making these offers to members of Parliament to buy out their votes," Grewal told CTV News Vancouver on Sunday --his first public statement in days.

Grewal has accused the Liberals of making an offer to him and his wife, also a Conservative MP, in exchange for their abstention on the critical budget vote last Thursday.

He said the conversation took place with Tim Murphy, Prime Minister Paul Martin's chief of staff.

"He made two offers -- diplomatic, as well as a senate position for my wife. Even a cabinet position."

Grewal also said he spoke for about two hours with federal Health Minister Ujjal Dosanjh, a fellow B.C. MP.

Grewal said he had no intention of accepting any offer, but strung the Liberals along to gather evidence.

The Criminal Code says it's an offence to offer a reward to an MP for a vote, but it's also against the law to accept a reward.

Murphy has hired a lawyer to protect his interests. He has refused an interview request.

But Health Minister Ujjal Dosanjh said Grewal made the first move and that the Liberals have done nothing wrong.

"The discussion obviously was started by him and we were carrying on the discussion within the appropriate framework," he said.

Both sides agree there was a go-between: Salish Kalia, a friend of both Grewal and Dosanjh.

On Thursday, Kalia said: "He (Grewal) said, 'yeah, if you can talk to someone, I'm interested'."

Grewal, however, has a tape of a phone conversation conducted between himself and Khalia in Punjabi that suggests Khalia would back Grewal's version of events if the matter ever became public.

"This would be enough for anyone to know, in a real sense, that the Liberals are making offers. And the proof is in the pudding."

Kalia has since issued a statement saying that conversation is being played out of context and called for Grewal to release more of the tapes.

Dosanjh wouldn't comment to CTV News Vancouver.

The whole mess had NDP spokesman Jamie Heath telling CTV's Question Period: "The best way to clear the air would be to have an independent investigation, probably the RCMP, to have a look at this."

The Conservatives haven't joined that call for a police investigation.

While there are up to four hours of tapes in total, Grewal has only released a few minutes of them.

"He won't say why and neither will party officials," said CTV's David Akin.

Grewal says he has the tapes, "but he says he's not allowed to play some of them at the request of the communications department of the Conservative Party," Akin said.

"He says he's talked to party leadership; he won't say exactly who. He says they've been involved in this entrapment process; he won't provide specifics about that."

As for the Liberals, this could turn out to be serious business if Grewal's allegations are true, Akin said.

"It could force some resignations in the Prime Minister Office, perhaps even a cabinet minister."

However, Tim Murphy, Prime Minister Martin' chief of staff, has denied making any offer, and "he's even suggested that he's considering suing Grewal if he continues with these claims," Akin added.

With a report from CTV's David Akin