Stephen Harper answers questions in Moncton on Wednesday. He announced $10 million in funding for the Fundy Trail. (CBC)

Prime Minister Stephen Harper said Wednesday he has no answers when it comes to controversy surrounding former prime minister Brian Mulroney's status as a card-carrying Conservative.

"I can't address that subject. I don’t honestly know the answer. I’ve been reading and hearing different things," he said.

Last month, reports said senior Conservatives sought out reporters to tell them that Mulroney had given up his party membership card.

Mulroney denied giving up his membership, saying he'll be a member of the party until he dies.

Subsequent reports suggested the issue sparked a split within the Conservative party.

The reports came ahead of last week's start of a federal inquiry into the business dealings between the former prime minister and arms lobbyist Karlheinz Schreiber, who is facing extradition for tax, bribery and fraud charges in Germany.

Harper said his government has behaved responsibly in its handling of the Mulroney-Schreiber issue.

"I think Canadians understand the government has taken a matter that is very difficult for ourselves, for our party, and handled it responsibly," said Harper.

He took a swipe at the Liberals, saying their "extreme" response was in stark contrast to Conservative actions.

"Mr. [Michael] Ignatieff and the Liberal party, when this matter first broke, were practically demanding that I throw Mr. Mulroney in prison without a trial," said Harper.

"Now they’re out there pretending that somehow they’re his best friends and they don’t agree with any of this."

Earlier this week, Ignatieff brought up the issue during a news conference, telling reporters Harper lacked respect towards Mulroney.