Scottish Economy Secretary Keith Brown is concerned that Westminster is planning to break-up the Green Investment Bank and provide its new owner with a quick profit.
Mr Brown wants the UK government to provide assurances that whoever takes over will remain committed to its core role and that 50 jobs at its co-headquarters in Edinburgh will be protected.
He has written to express his concerns that the transaction will result in an asset stripping exercise with significant financial rewards for any new owner.
The Green Investment Bank was set up in 2012 to provide capital that would ensure major projects could go ahead under the chairmanship of Lord Smith.
So far it has committed £770 million of its own capital and secured £3 billion in partnership with private investors.
In October it was reported that Australian bank Macquarie was the most likely buyer against a rival approach from a consortium which included the Pension Protection Fund, Lloyds Bank and Sustainable Development Capital.
The privatisation process was launched in June 2015 by the former business secretary Sajid Javid.
Mr Brown said: “I am extremely disappointed with the approach that the UK Government has adopted around the sale of the Green Investment Bank, which has been characterised by an unacceptable lack of communication throughout.
“In 2015 the then Secretary of State for Business Innovation and Skills gave assurances that he would work to protect the bank’s green purpose, as well as continuing to headquarter the Bank in Edinburgh, not only supporting 50 skilled jobs for Scotland’s capital, but also recognising Scotland’s place at the vanguard of the UK’s green economy.”
He said there were “reports that the privatisation has become more of a fragmentation or asset stripping process which runs counter to the previous commitments made to the Scottish Government
“This is deeply troubling considering the vital role that the Bank serves in our green economy.
“The veiled manner in which privatisation is taking place offers no reassurance that the future of the Green Investment Bank is being modelled in line with the reassurances offered to the Scottish Government in 2015 which state that the original purpose of the bank would be maintained.
“The UK Government should update the Scottish Government on the progress of privatisation and provide clarification that previous assurances are being adhered to.
“I also want to be absolutely clear that the Scottish Government will voice any concerns and continue to apply pressure to ensure that our objectives remain a priority as part of the privatisation process.”