Bright Food's $1.5bn (NZ$1.88bn) move to buy CSR's sugar and renewable energy unit - including a majority stake in the operation that owns the Chelsea brand and Auckland refinery - has been knocked back by the iconic Australian company.

Shares in CSR jumped on the news, bucking the overall down trend on the market to gain 3 cents, or 1.5 per cent, to $2.01 shortly after the market opened.

In a statement released to the Australian Securities Exchange this morning, CSR said it had considered the offer from the Chinese food giant - but its preferred option remained an existing demerger proposal for its sugar and energy business.

"CSR remains focused on maximising shareholder value," the statement said. "...(T)he Board is of the opinion that the demerger is in the best interests of shareholders."

Analysts have speculated the move could attract interest from foreign food companies, including Brazil's Consan, Bunge and Cargill.

"(CSR's) statement is a tactic which, rather than discourage buyers, will cause them to be more forthright in putting forward both a stronger offer and a more formal offer," said White Funds Management portfolio manager Angus Gluskie.

"The last week has shown us there's clearly interest such as this at a global level," he added.

In a separate announcement to the exchange, CSR explained that news of Bright Food's interest - which was announced on Tuesday - was revealed publicly by Bright Foods through statements to the media.

CSR stock jumped 4.3 per cent on that day, before giving back most of the gains - 3 per cent - the following day.

''CSR did not receive notice of the Media Statement or Letter until the morning on Tuesday 12 January 2010 and was not provided with any prior notice that the possibility of receiving such an approach from Bright Food may occur,'' the response to the ASX's please-explain said.

''Certain officers of CSR first became aware of the Letter shortly before 9am AEDT on Tuesday 12 January 2010.''

The letter went on the say the chairman and a financial adviser had received copies of Bright Food's expression of interest between 8.30 and 9am on that day.

''CSR now understands that the Media Statement was released to several news wires at approximately 9am AEDT on Tuesday 12 January and that the news wires publicly from approximately 9.04am...''

CSR, also a building products maker, announced in June last year a plan to split into a separate company its sugar business, which accounted for around 60 per cent of Australia's 4.2 million tonnes of raw sugar output in 2009.

Adgent007_300x250NZXSitewide_150909.html CSR aims to spin-off the sugar business by March and has already raised about $375 million in fresh equity to enable the two listed companies the demerger will create to have appropriate levels of debt.

BusinessDay and Reuters