The denial came a month after a ban on further M&S approaches by Mr Green - imposed by authorities after his �9bn approach collapsed in July - ended.

He did however say in a statement that he reserved the right to make an offer if a third party expressed interest.

At the same time, a little-known South African firm said it had potential backers for a management buyout of M&S.

In a statement, Cape Town-based venture capital group Paulsmeier said it had been approached by "certain staff members" at M&S.

The group said it now had a potential financier in place for a �10.5bn ($20bn) offer and chairman Marc Paulsmeier would be in London in the last week of February to tie up any loose ends.

M&S said it had no comment to make about the South African company's claims.

'Bizarre'

Retail analyst Matthew McEachran of Investec Securities said news of a potential buyout at M&S backed by a South African firm was "bizarre to say the least".

"No-one has any idea exactly who at M&S is said to be considering an MBO, but it is hard to believe that it would be (chief executive) Stuart Rose or anyone else on the board.

"Apparently, it is a more junior member of management, but no-one really knows."

Shares in M&S ended up 1.77% to 374p on Tuesday.