THE Football Association said last night it would investigate allegations of transfer impropriety made against Sunderland by Tranmere Rovers yesterday if the Second Division club lodges a formal complaint over the Premiership club's move to sign their Republic of Ireland Under-18 international Sean Thornton.

The Wearsiders have been accused of "poaching" the 18-year-old midfielder - and the angry Merseyside club is threatening to report the Premiership outfit to Soho Square.

Thornton, whose contract at Prenton Park expires next month, trained on Wearside last week and is believed to have agreed personal terms after passing a medical.

But Tranmere boss Dave Watson is furious about the way Sunderland have tried to sign the club's prize asset, moving in for the 18-year-old midfielder ahead of rivals Arsenal, Manchester United and Liverpool - even though players approaching the end of their contracts can open negotiations with other clubs.

But unlike a Bosman free transfer, clubs can claim compensation for the training and development of players under the age of 23.

Watson - a former teammate of Sunderland manager Peter Reid at Everton - fumed: "It seems that Sunderland have tried to snatch our player by making an illegal approach.

"Both Sean and Sunderland have shown a complete lack of respect for Tranmere Rovers and the FA and Football League rules, which is totally out of order.

"This is a dreadful way for Sean to treat Tranmere after the opportunity we have given him and the record-breaking contract we have been discussing with him."

Tranmere chairman Lorraine Rogers said: "If Sunderland want Sean Thornton they will have to pay compensation.

"We have a very strong case and we will let a tribunal decide if necessary."

She added: "Sunderland have shown a total disregard for the rules and we hope they will be made to pay for their actions.

"Sean has let down every Tranmere Rovers supporter - whilst they have been paying his wages he has been training with another club and agreeing terms without our knowledge or permission."

Thornton, who has played only nine first team games for Tranmere, has admitted talking over a transfer with Sunderland, where he would link up with Irish internationals Niall Quinn, Kevin Kilbane and Jason McAteer.

He said: "It has been my dream to play in the Premiership and hopefully that will become a reality now with Sunderland.

"It's a chance I could not turn down."

A Sunderland spokesman said: "Sunderland and Tranmere Rovers have had on-going talks regarding a compensation fee for the transfer of Sean Thornton and the last set of talks took place only last week."

A spokesman for the FA said yesterday: "Without knowing all the facts of the matter all I can say is that if Tranmere Rovers decide to make a formal complaint we would look at it with regard to the relevant transfer regulations."

If the two clubs cannot mutually agree a fee by the end of next month the case will go before a Football League Appeals Committee tribunal.

l Sunderland midfielder Thomas Butler, who marked his full Sunderland debut by laying on the equalising goal in the 2-2 draw at Charlton, has been told he can join up with the Republic of Ireland Under-21 squad in Toulon, France, immediately after the last Premiership game of the season against Derby County at the Stadium of Light a week on Saturday.

Sunderland need a point to make sure of staying above third-bottom Ipswich Town, whose last game is against Liverpool at Anfield.

l A question mark hangs over the future of West Brom manager Gary Megson after another reported bust-up with chairman Paul Thompson.

Megson, who guided the Baggies into the Premiership, is reported to have walked out of clear-the-air talks with club directors yesterday after just 15 minutes.

His relationship with the board has become increasingly strained over the last few weeks with disagreements over the club's training facilities and scouting system souring celebrations