Newco Rangers chief executive Charles Green faces a fresh blow in his battle to hold on to the the club's wantaway players - including new Saints signing Steven Davis - as his purchase of their contracts is not valid, according to an employment law expert.

The club's administrators, Duff and Phelps, revealed earlier this week that Green's £5.5million purchase of Rangers' assets included a £2.75m payment to purchase the contracts and registrations of the players.

Duff and Phelps, appointed by the Court of Session on February 14, broke down all the "asset realisations" and it was shown that Green's consortium paid for the club's employees to transfer to his company under TUPE regulations, which protects employees' terms and conditions of employment when a business is transferred from one owner to another.

However, on the advice of their union, PFA Scotland, numerous players have rejected the opportunity to transfer their contracts from Rangers to Green's Sevco consortium.

Green rejects the claim that the players are free agents and the former Sheffield United chief executive sent letters to clubs across the UK warning them that the players who objected to the switch to his new company were in breach of contract.

International clearance for the transfers of Davis, Kyle Lafferty, Jamie Ness, Steven Whittaker and Steven Naismith has been put on hold as Green continues to dispute the players' status.

Naismith has moved to Everton, Whittaker has signed for Norwich and Ness has joined Stoke.

Northern Irish duo Davis and Lafferty are at Saints and Swiss side Sion respectively, while goalkeeper Allan McGregor is in talks with Turkish club Besiktas.

Despite Green taking a firm stance, Adrian Hoggarth, the head of employment law at Prolegal believes the deal struck may have been outside of the law.

"It is not legally possible for Rangers and Charles Green to buy and sell players as part of a business transfer," he said.

"Whether or not the players transferred in this case appears to depend on two things.

"Firstly, were they assigned to the business of the football club when it transferred? This is a matter of law and this has nothing to do with any money that may have changed hands.

"Secondly, were the players aware of the transfer at the time it took place? Case law suggests that if you know about a transfer before it happens and don't object to it, you lose the right to object once the business transfers. If not, you don't.

"To suggest otherwise would take away the right of an employee to object to being transferred, which is a right enshrined in law."