A troubled mining company that was the subject of a major corruption inquiry has warned foreign companies they could lose money invested in NSW's electricity assets, claiming the sovereign risk is akin to that in nations ruled by despots.

The admonition by NuCoal comes as NSW Treasurer Gladys Berejiklian is due to face hostile questioning over the controversial power plan when she appears at a parliamentary inquiry on Monday.

NSW Treasurer Gladys Berejiklian is due to face hostile questioning over the controversial power plan. Credit:Ryan Osland

The Baird government intends to part-lease the state's electricity distribution and transmission businesses, known as the "poles and wires", which dominated its re-election agenda.

It has invited global interest in the plan, which would raise an expected $20 billion to be spent on big-ticket infrastructure items such as a second Sydney Harbour rail crossing.