The Edinburgh-based bank was set up with public money and has generated a 10% return on its £2.7bn portfolio of environmental projects, but is set to be sold to Australian group Macquarie this month.
However, reports that individual investments are being touted for sale to third parties have raised concerns that the bank could be broken up.
UK Green Party leader Caroline Lucas led calls for the sale process to be halted, warning the bank’s purpose as a green investment vehicle could be “fatally undermined”.
Ms Lucas claimed Macquarie has a “very worrying and dubious track record” and was unlikely to continue investing in environmental projects.
She was joined by SNP MP Joanna Cherry, who demanded assurances over the future of 55 staff in Edinburgh, and Labour’s Ian Murray, who warned private investors “won’t touch” the green schemes supported by the bank.
Energy Minister Nick Hurd said the government will retain a “golden share” in the, and insisted privatisation would boost its “green impact”.