NEWCASTLE’S attempt to sign Mike Williamson was on the verge of collapse last night after Portsmouth’s financial problems forced them to pull the plug on the defender’s proposed move.

And with fears over the extent of Steven Taylor’s ligament injury growing, the Magpies could be forced to look at alternative targets which are understood to include their former centre-half Andy O’Brien and Stoke City’s Leon Cort.

Williamson successfully underwent a medical on Tyneside yesterday after Pompey accepted the Magpies’ offer of £925,000 on Thursday night.

Newcastle officials had hoped to complete a deal yesterday evening after a successful round of personal negotiations with the centre-half and his representatives, but their plans were scuppered when Portsmouth effectively pulled out of the deal.

Despite having agreed to sell Williamson on Thursday evening, Pompey performed an abrupt about turn after the full extent of their obligations in the wake of the defender’s proposed departure became clear.

Portsmouth signed Williamson from Watford for £3m last summer but, like so many of their deals during that time, the south coast club paid little or nothing of the money up front.

Watford also inserted a sellon clause in the deal that took Williamson to Fratton Park, so while Portsmouth would be due to receive £925,000 if they sold the 26-year-old to Newcastle during the current transfer window, they would also be due to pay the Hornets around £2m.

As a result, the deal was in major doubt last night, despite a day of hectic negotiations between officials from Newcastle, Portsmouth and Watford.

But in order for a deal to be concluded, either Watford will have to write off a considerable amount of money or Newcastle will have to up their bid considerably, neither of which looks particularly likely.

Alternatively, the two clubs could agree to a loan deal until the end of the season, which would prevent the need for Portsmouth to pay Watford immediately.

It was hoped that Avram Grant would shed some light on the situation during his scheduled press briefing yesterday, but the Pompey boss failed to appear to preview this afternoon’s FA Cup fourth-round tie with Sunderland.

There were rumours that the former Chelsea boss was considering his position, but Portsmouth director of communications Gary Double insisted there was nothing sinister in the Israeli’s no-show.

Double said: “He said there is nothing more to add and he has spoken about everything.

He knows the questions are all going to be about off-thefield stuff.”

Newcastle had hoped to sign Williamson in order to provide some cover to Chris Hughton’s first-choice centrehalf pairing of Steven Taylor and Fabricio Coloccini.

With Zurab Khizanishvili having returned to Blackburn Rovers following the end of his loan spell, Tamas Kadar currently represents the Magpies’ only central defensive cover.

That could be significant in the second half of the season as fears are growing over the extent of the injury Taylor suffered during a collision with Roman Bednar in Monday’s draw with West Brom.

Taylor will miss today’s game and Newcastle’s medical staff are awaiting results of tests that could lead to a lay-off that will be measured in months rather than weeks.

Kadar is expected to partner Coloccini in today’s FA Cup fourth-round tie at West Brom, and Hughton last night defended his sparing use of the highly-rated Hungarian.

Kadar has started just four matches in all competitions this season, but Hughton feels it is important not to push him too hard, too early.

“He’s young and a player we see as a developing player,”

said the Newcastle boss.

“It’s a tough league this one and we’re talking about a young player in a position that’s generally what you call a man’s position.

“You see a lot of good tough centre-halves in this division, and we feel the development we’re giving him is right for him.

“He has ability, there’s no doubt about that. If we felt he was ready and the finished article, he’d have played more games, but we feel our approach is the right one, particularly given the position he plays.”

Tim Krul will take over from Steve Harper in goal this afternoon.

But Peter Lovenkrands will miss the trip to the Hawthorns after being given compassionate leave following his father’s funeral on Thursday.