Ambrose given Newcastle green-light
The Magpies swooped to sign Ambrose last month, just before the Nationwide League's transfer deadline, from Ipswich.
The Premiership's own deadline was the end of January - but Ipswich are in administration so they were allowed to sell players because they are classed as a club in 'distress'.
Newcastle took advantage of this by signing Ambrose and Charlton Atheltic also capitalised with the capture of Hermann Hreidarsson, although The Addicks are now allowed to use their latest signing.
The Premier League have told planetfootball.com that they had their own deadline, which was Monday March 24 - the day Ambrose signed - although the Nationwide deadline stretched until March 27, which is when Hreidarsson signed.
The news of Ambrose's availability is sure to anger the likes of Arsenal and Manchester United who are embroiled in The Premiership title race with Newcastle.
Newcastle manager Sir Bobby Robson was delighted with the news as admits Ambrose could have played this weekend, had he not been ruled out with a knee injury.
"To tell the truth, I am a bit surprised that we can use him for the rest of the season," said Robson.
"But the chairman has pulled it off - and it goes without saying I am delighted.
"If Nobby Solano had not been fit for Sunday I think I would have played Ambrose wide on the right for us against Everton.
"But he has had a nasty bang on the knee and we have got to get the swelling down before we can train him and play him.
"He is a very good player and I don't think he will be fit for another week.
"He has not trained for a month, and once we get the swelling down on his knee we will build up his fitness.
"But everything depends on how quickly we can get that swelling down."
In other news, Newcastle have announced a new two-year sponsorship deal with the Northern Rock bank.
The Newcastle-based company have bought out the final two-years remaining on current sponsors NTL's contract - who have been associated with United for the last three years.
