M&S chief executive Stuart Rose has reservations about whether to enter the fray, The Times reported, but it is thought the retailer sees opportunities in Sainsbury's property portfolio.
M&S has not appointed bankers to assist with a deal and it is thought the idea is unlikely to progress further unless there was dissatisfaction among Sainsbury's investors with the price offered by the private equity firms. The consortium, comprising CVC Capital, KKR and Blackstone, is understood to be preparing a deal worth as much as£10 billion.
A bid for Sainsbury's by any of its grocery rivals - Tesco, Asda and Morrisons - would likely be impossible on competition grounds. However, M&S would probably be allowed to proceed.
Rose has successfully steered M&S to revival since taking the helm in 2004, but has been cautious about describing the improvements as a fully fledged recovery. He would think carefully before jeopardising his achievement by taking on the burden of another big store group in the middle of a reinvigoration programme.
M&S declined to comment.
Sainsbury's has accused the Competition Commission of being unable to add up, The Telegraph reported. The grocer made its claim after the Commission disputed its forecast that Tesco's market share could reach 43 per cent by 2010. Sainsbury's said the regulator had used 'fundamentally and materially different assumptions' and created 'a misleading impression'.