Portsmouth are on the brink of being sold to a consortium led by the head of one of South Africa’s largest gold-mining companies. The Times has learnt that Greg James, the chief executive of Central Rand Gold, is the man leading a £70 million takeover bid that will cast immediate doubts over the future of Tony Adams as manager.

James has held a series of discussions with Alexandre Gaydamak, the Portsmouth owner, in the past week and is understood to be confident of striking an agreement to buy the club from Devondale Investments, the holding company. He is being assisted in negotiations by Pini Zahavi, the influential Israeli agent, who knows both men well and may be retained in a consultancy role if the bid is successful.

The bid, which includes provisions for writing off the club’s debts, reported to be £32 million, is understood to be progressing well, although Gaydamak has still to receive guarantees over certain elements of the offer. Club officials remained in the dark last night, declining to comment. Neither could James or Zahavi be reached.

A second takeover in less than three years would be welcomed by many at Fratton Park, with The Times having revealed in January that Gaydamak was looking to sell the club. Adams may not be among them; the former England captain took over as manager a fortnight ago after Harry Redknapp quit to join Tottenham Hotspur, but his position would be thrown into doubt if the takeover bid is successful.

Potential managerial targets would include Avram Grant, who served as director of football at Portsmouth before his spell as first-team coach at Chelsea, and Slaven Bilic, the Croatia head coach. Grant, who has close links with Zahavi, is understood to have asked Hajduk Split, who have offered him the manager’s job, if he can delay giving an answer for two weeks while he explores other options.

It is not clear whether James, who describes himself as a rugby union enthusiast rather than a football fan and lives in Switzerland, would take a hands-on approach if he succeeds in buying Portsmouth, but a source confirmed his intention to do so. “He’s a very serious, very rich man and he wants to buy a football club,” the source said. “Portsmouth fits the bill and things look very positive.”

Gaydamak made similarly bold noises when he bought Portsmouth in January 2006, but Redknapp confirmed last month that the club are operating under increased financial constraints, with the wage bill having risen dramatically over recent years. The prospects for increased revenue are limited until the proposed relocation to a new 36,000-capacity stadium at Horsea Island is confirmed.

Keith Harris, chairman of Seymour Pierce, the investment bank, was initially entrusted by Gaydamak with trying to find a buyer. Harris is understood to have presented Gaydamak with a series of options, but the owner has expressed his preference for the bid headed by James and other South African businessmen, plus Zahavi.

South Africa would represent a new addition to the list of nationalities owning Premier League clubs, but, with a series of other potential takeover bids being overseen by Harris or by Amanda Staveley, the sport’s two main powerbrokers, that invasion is certain to continue in the coming months.