NSW Treasurer Gladys Berejiklian is trying to allay security concerns over the prospect of a Chinese government-owned company buying high voltage electricity company Transgrid, insisting the government is "proactively engaging" with the Foreign Investment Review Board on the issue.

Bids for Transgrid, which is being offered on a 99-year lease by the NSW government, are due on Monday. The government is hoping to get about $9 billion from the transaction, which is expected to be completed before the end of the year.

NSW Treasurer Gladys Berejiklian would not speculate on potential bidders. Credit:Daniel Munoz

Among the likely bidders is State Grid Corporation of China, which is in a consortium with Macquarie Bank's infrastructure arm.

Transgrid's role in supplying power to Canberra and its extensive fibre optic cable network carrying sensitive data for government departments has prompted security concerns about selling to a Chinese government-owned entity.