Delta says it supports Sainsbury's operational strategy

The fund, which already owns 25% of the supermarket's shares, is still planning an offer of 600p a share.

Speculation about Sainsbury's future has been swirling since investors called for it to be split up, and the Qataris first made a move in July.

A private equity bid, led by CVC, was rejected in the spring.

'Substantial investment'

The supermarket giant said that there was no guarantee a definite offer for the firm would be made.

But Sainsbury's chairman Sir Philip Hampton said he believed that if a firm offer did materialise, the bid would be recommended to shareholders.

Delta has revised its proposal to fund the deal with �4.85bn in shares and payment-in-kind notes. However, the deal would still be largely backed by debt.

This is an important next step in our progressing a possible offer Paul Taylor, Delta Two

Delta said that if the deal went ahead, former Asda deputy chief executive Tony Campbell would become a non-executive chairman.

Sainsbury's would see "significant investment and further expansion" and would remain "a robust competitor... even in challenging industry conditions", Delta said.

Amongst the most vocal investors behind a deal has been property tycoon Robert Tchenguiz, who owns a 5% stake in the company and wants Sainsbury's to separate its retail operations and real estate holdings.

That would allow the company sell off property holdings, returning cash to shareholders, analysts say.

Delta Two is run by Paul Taylor, a former employee of Mr Tchenguiz.

Mr Taylor said that Delta was pleased to have been given access to Sainsbury's books.

"We have a high regard for the management and employees of Sainsbury's and we are supportive of their operational strategy, including plans for substantial investment in the company," he said.

"This is an important next step in our progressing a possible offer."