The changes will be considered by Prime security holders at an extraordinary meeting next Thursday.

The Australian Council of Super Investors, Institutional Shareholder Services and Corporate Governance International have said they doubt the proposed changes would deliver a sufficiently independent board.

Prime last week said associate company Babcock & Brown wanted to establish a B & B-branded ASX listed infrastructure fund and offered Prime security holders the opportunity to restructure Prime Infrastructure. Prime’s independent directors believed the advantages of the restructure outweigh the disadvantages.

The proposals would allow Babcock & Brown to appoint the chair of the newly named and restructured Prime entity, something the investment groups say will give the investment bank up to 75% at board level.

But Chris Chapman, managing director of Prime Infrastructure Management, said it was incorrect that Babcock & Brown would unilaterally get the right to appoint three quarters of the new board.

Prime – which bought New Plymouth-headquartered energy network company Powerco late last year – estimated the restructuring should be complete by July.