National Australia Bank shareholders overwhelmingly voted to spin off troubled British asset Clydesdale Bank Wednesday, ahead of a partial float of the business expected next week.

More than 97 percent of shareholders voted for the proposal, which will see 75 percent of Clydesdale demerged to NAB shareholders, who will be given shares in the bank, one of Scotland's largest.

The remaining 25 percent will be sold through an initial public offering (IPO) to institutional investors.

NAB chairman Ken Henry said Wednesday ahead of the vote that the demerger was "likely to enhance value for shareholders over the long term", with Clydesdale, which NAB bought in 1987, "repositioned... for a standalone business".

The IPO is expected to take place on February 2, with shares set to begin trading on the London Stock Exchange (Other OTC: LDNXF - news) within a week.

"Clydesdale Bank has been a significant factor in NAB shareholder returns not being at the level that we have wanted, nor competitive with our Australian peers," Henry said.

"This demerger and IPO will allow acceleration of NAB's exit and presents the most certain outcome for NAB shareholders."

NAB shares closed 3.10 percent lower at Aus$26.90 in Sydney on Wednesday.

The Australian lender outlined plans to divest Clydesdale in October as it posted a 19.7 percent lift in annual net profit to Aus$6.34 billion (US$4.45 billion) for the year to August 31.

"The real strategy has been to clean up some of their issues from the past and refocus the business back on the Australia-New Zealand core franchise," analyst Omkar Joshi of Watermark Funds Management told AFP.

"The UK business was really the last piece, given they've already done a lot of the other things. So the fact that they are demerging it now is positive."