Sir John's resignation raises a question mark over the club's future ownership. His company, Cameron Hall, still owns a majority stake in the club.

It is yet another blow for the Premier League club which has now lost seven senior executives in the last 12 months and been rocked by scandal when two executives, including Douglas Hall, Sir John's son, allegedly lampooned the club's fans and players.

Sir John came back to the club in the turmoil that followed the resignation of Douglas Hall and fellow director Freddy Shepherd.

Sir John said he would stay until the end of May, but there had been growing speculation that he would continue until the situation stabilised.

Sir John's second spell as chairman has ended in controversy when two directors of the parent company quoted on the stock exchange - former Rolls Royce head Sir Terrence Harrison and John Mayo - left suddenly last week.

New directors

Newcastle United said it was looking for two independent non-executive directors following the departures of Sir Terence and Mr Mayo.

In a statement to the stock exchange, the company said it planned to meet "to consider the structure and complement of both the plc and the football club boards" immediately after new appointments were in place.

The latest move raises a question about Sir John's plans for his stake. But, under terms of Newcastle's float agreement, the Hall family cannot start reducing its holding until this December to ensure stability at the company.

Football analyst Vinay Bedi at stockbroker Wise Speke said: "I don't think anyone knows who will be on the board in two months' time."