Tuesday is the final day of the inquiry looking into the business dealings between Brian Mulroney, left, and Karlheinz Schreiber. (Jonathan Hayward, Kevin Frayer/Canadian Press)

The public inquiry into German-Canadian businessman Karlheinz Schreiber's dealings with former prime minister Brian Mulroney is holding its final hearing in Ottawa on Tuesday.

The Oilphant Commission is hearing testimony from Sue Gray, director of the Propriety and Ethics Team of the U.K. cabinet office as well as from Canada's ethics commissioner, Mary Dawson.

During the inquiry, Schreiber has testified he gave Mulroney $300,000 to lobby the Canadian government to build a light-armoured vehicle plant on behalf of Thyssen Industries. Schreiber says he struck the deal with Mulroney before the prime minister left office, although the money didn't change hands until later.

Entering into an agreement while still in office to lobby the federal government on behalf of Schreiber would be an apparent violation of the ethics standards Mulroney implemented after taking power in 1984.

Mulroney told the commission he accepted $225,000 in cash from Schreiber to promote the sale of those vehicles internationally. He testified he didn't ask for cash and said there was nothing "sinister" in accepting it.

Mulroney admitted to taking the sum but not reporting the cash payments for income-tax purposes until six years after he started getting them.

Mulroney said he broke no laws or ethical guidelines and confined his lobbying to foreign political leaders in search of export markets for the Thyssen vehicles.

The government has promised not to extradite Schreiber until the conclusion of the inquiry. It's never been clear whether that ruling by Justice Minister Rob Nicholson meant until the end of the judge's work or just until the conclusion of the public hearings and Schreiber's testimony.

Schreiber is wanted in Germany on charges of fraud, bribery and tax evasion. He lost his latest attempt to stay in Canada after the Ontario Court of Appeal rejected his request for a judicial review of his extradition order earlier this month.

Justice Jeffrey Oliphant has said it would be a "travesty of justice" if Schreiber is booted from Canada before the commission's work is finished.

The deadline for Oliphant's report to the federal government is Dec. 31.

With files from The Canadian Press