Sheffield United have launched a legal challenge over the Premier League's failure to hand West Ham United a points deduction for breaching ownership rules over Argentines Carlos Tevez and Javier Mascherano.

The club was relegated from the Premier League at the weekend after a 2-1 defeat to Wigan and a Tevez inspired win for West Ham at Old Trafford.

Following the resignation of manager Neil Warnock this morning, the club announced that it has sent an arbitration notice to the Premier League.

The Blades are aggrieved that West Ham were fined £5.5 million instead of being docked points for involving a third party in the transfer of the two Argentineans.

"We've not been playing under the same circumstances as everyone else in the Premier League. It's about time that the Premier League recognised that exceptional circumstances have occurred. The groundswell of support throughout sport is that a club has been wronged," Sheffield United chairman Kevin McCabe told reporters.

"We shouldn't have to pursue litigation. A club who've played by the rules has been relegated at the expense of one club who've fielded ineligible players. They should call us in and start to work out what needs to be done next."

McCabe suggested that one possible solution would be to retain Sheffield United in the Premier League and relegate four clubs at the end of next season.

There was no immediate comment from the Premier League.

In a bid to secure further support, McCabe has ensured that politicians have been made fully aware of the case.

"We've written to every MP, advising them what has gone on," McCabe added. "We're doing everything to protect the interests of Sheffield United."

He said the matter had been a major factor in Neil Warnock's decision to step down as manager.

"What's happened off the field has hurt him and he goes with our blessing," McCabe said.