Newcastle owner Ashley has insisted he will hold out for the right price
Prospective bidders for Newcastle have been given until 17 October to register a firm interest in the club.
It is believed eight parties have contacted investment bankers Seymour Pierce, who are acting as sellers, to show their intentions.
However, the extension of the period of interest means the completion of any sale may not take place until the end of November.
Owner Mike Ashley is believed to want about £280m to £300m for the club.
He put the Magpies up for sale in the wake of the sudden departure of former manager Kevin Keegan but has insisted he will hold out for the right price.
A four-page 'teaser' document has been handed to interested parties, who have been asked to sign a confidentiality clause, outlining what is involved in buying the club.
Last week, interim manager Joe Kinnear suggested that his reign at the club could run to 10 or 12 matches, rather than being six to eight as was first thought.
On Friday, three South African businessmen linked with a possible £300m takeover denied they had any intention to buy the club, with billionaire Johann Rupert saying he had "absolutely no interest and no knowledge".
The South African group were considered to be the frontrunners - with their interest in bringing Keegan back making them popular with the fans.
A Nigerian consortium was also believed to have presented its bid of about £350m to the club.
Bookmark with:
What are these?