Former New South Wales mining minister Ian Macdonald has told a corruption inquiry into mining tenders that he is not a crook.

In a day of fiery exchanges, Mr Macdonald was accused of personally drawing up mining exploration leases to favour the family of former Labor colleague Eddie Obeid.

It was the second day in the witness stand at the Independent Commission Against Corruption (ICAC) for Mr Macdonald, who now lives in Hong Kong.

Counsel-Assisting Geoffrey Watson made his way through more than three dozen points which he said would help prove Mr Macdonald rigged a mining tender to the benefit of Mr Obeid.

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One of those points was the allegation that confidential maps were found in the Obeid family's office. Mr Macdonald said he did not give the Obeids the maps.

At one stage Mr Watson asked Mr Macdonald if he was a crook, to which he replied: "That's an absolute lie."

But perhaps the most devastating words came from the mouth of Mr Macdonald himself when he conceded that he had provided confidential state secrets to the Obeids.

Having made that concession, Mr Macdonald said he had no idea how that information would be used.

The claim was met with disbelief, anger and frustration from the commission, while from the public gallery it was lampooned like a comedy show and some observers laughed openly in the face of the answers.

Commissioner David Ipp reprimanded Mr Macdonald for not answering simple questions and warned him the inquiry would sit until he did.

When asked to explain why the Obeids let him stay at their ski lodge for free and paid his food bill of around $800, he said it was hospitality and he would have done the same for them.

The former minister said he had no idea a mining tenement was over land in the Bylong Valley owned by the Obeid family until he read it in a newspaper.

He said the creation of the Mount Penny tenement "just happened" and that he did not know they owned the land.

Mr Macdonald admitted he did not tell state parliament nor the Labor Party that the tenement was over Mr Obeid's property because he saw no reason to and no-one asked him.

Some of Mr Macdonald's former staff have told the inquiry that he rejected advice not to create the Mount Penny tenement over land owned by the Obeids.

Mr Macdonald denied that was the case.

When it was suggested to him that one of his former staffers was an honest man of great integrity, Mr Macdonald replied: "So am I."