NEWCASTLE United were last night hit by fresh fears over the fitness of Kieron Dyer.

The England star, who was this week cleared to play on after undergoing rigorous tests for shin splints, failed to return to training yesterday.

And United manager Bobby Robson admitted he is "worried'' about the 22-year-old midfielder, whose reintroduction to full training has now been delayed until Monday.

That means Dyer may not be ready to return to action in next Wednesday's clash with Chelsea at Stamford Bridge.

Robson said yesterday: "We hoped he would return to training this morning, but he hasn't.

"The medical staff asked us to keep him out until Monday, so he can have three more days of complete rest. In terms of football, he's doing nothing.

"The next three days will benefit him, but I'm a bit worried that he is not doing any football work.

"However, we are aware that it could have been much worse. We feared he had a stress fracture instead of a cyst on the shin.''

Prize asset Dyer, who Newcastle are said to value at £22m, has now missed a fortnight's training and, despite a specialist's report assuring him that his condition is not serious, United won't be happy until he is playing regularly without discomfort.

Meanwhile, furious Newcastle officials have launched a top-level investigation into claims that Nolberto Solano's EU passport may be invalid.

The Peruvian winger insists he qualifies for his Greek passport through his paternal grandmother.

But only direct parentage applies and, with Solano's work permit having run out, it is feared he could be forced to leave Britain while a new permit application is processed.

Solano, a £2.5m Kenny Dalglish signing from Argentinian side Boca Juniors nearly two-and-a-half years ago, has been United's key man this season and is hoping to net a new deal worth around £28,000-a-week.

The 26-year-old was this week named ntl Newcastle Player of the Month for December and head coach Mick Wadsworth underlined how important Solano is to the club.

He said: "Nobby's consistency level has been as high as it ever has since I came to the club last season.

"He gives us that extra little spark of creativity and he's a super player who thoroughly deserves his recognition."

Robson added: "He has quality, that touch of magic which marks all outstanding players. His ability, either on dead-ball kicks or crossing and shooting, stands him apart."

l Defender Olivier Bernard wants to win a new deal with Newcastle after emerging from a nightmare.

The Frenchman was at the centre of a row with former club Lyon when he agreed a one-year contract on Tyneside early in the season.

Lyon refused to release Bernard's registration and FIFA were forced to intervene on Newcastle's behalf.

A hamstring injury then kept Bernard on the sidelines.

But he strengthened his contract case by performing well in the presence of Bobby Robson as United Reserves drew 1-1 with Manchester City at Kingston Park on Monday.

Bernard, 20 next week, confirmed: "I like it here and I want to win an extended contract. I took a bit of a risk coming to Newcastle because I could have signed a longer contract at Lyon. But I knew Newcastle were short of left-sided players and I wanted to try my luck in England.

"It has been difficult for me in the last few months but I want to play well for Newcastle and show that I am good enough to stay longer."

l Greek centre-back Nikos Dabizas is due to return to Newcastle next week to step up his recovery from a cruciate injury which has kept him out since August. United had effectively ruled Dabizas out for the season, but he now hopes to be playing again in about a month's time