The 56-year-old was a hugely popular figure during his first spell as Magpies boss from 1992-1997 but was ranked as an outside candidate to replace Sam Allardyce, who left St James' Park last week after an unsuccessful short stint in charge.

Gerard Houllier and Didier Deschamps were strongly linked with the position in the last two days but the club unexpectedly announced Keegan as the club's new manager on their website on Wednesday afternoon.

Keegan was linked to the role but initially only in partnership with legendary striker Alan Shearer.

Keegan took Newcastle to promotion back to the top flight in 1993 and came close to winning the league title in the 1995-96 season when they famously led Manchester United by 12 points before finishing as runners up.

He went on to manage Fulham, England and Manchester City but has been out of the game since leaving City in 2005 after a largely unsuccessful spell.

Harry Redknapp had been first choice for owner Mike Ashley and chairman Chris Mort but he last week opted to stay at Portsmouth.

That only fueled increased speculation about possible contenders with Mark Hughes, Houllier, Deschamps and Shearer being mentioned most prominently.

The message coming out of the club was that experience was the main prerequisite - instantly making Shearer a more unlikely candidate.

The 37-year-old confirmed when he revealed he had been told as much in a telephone call last week, although he added he believed he could galvanize the dressing-room.

Mort, in issuing what was effectively a job specification on Tuesday, also hinted that the likes of former Chelsea boss Jose Mourinho were not on the club's radar.

Former chairman Sir John Hall, whose family's decision to sell their holding in the club to Ashley sparked his £134.4million takeover bid, earlier said he felt Houllier and Shearer would be the ideal partnership.

But with Keegan surprisingly being given the task of reviving the club's fortunes, he will be keen to step into the role quickly to maximize the remainder of the transfer window.