The Carlos Tevez saga took another twist yesterday with the announcement by the Premier League and Football Association of a fresh investigation into the conduct of West Ham United.

In theory it could mean that West Ham face further sanctions — beyond the £5.5m fine imposed by the Premier League in its initial inquiry — such as a points deduction although the possibility of that happening are, according to various sources, extremely remote.

The inquiry will centre on the comments made by Lord Griffiths, the former judge who chaired an arbitration tribunal which ruled in favour of Sheffield United, who are seeking compensation for their relegation from the Premier League in 2007 during the time that Tevez played for West Ham.

The key point to be investigated is the evidence provided to the tribunal by the lawyer Graham Shear, solicitor for Tevez's adviser, Kia Joorabchian.

Shear claimed that Duxbury had provided verbal assurances that the third-party agreement still existed — in breach of league rules — despite West Ham having informed the Premier League that the deal had been terminated.

Griffiths said in his findings: "If the Premier League had known what Mr Duxbury for West Ham was saying to Mr Joorabchian's solicitor following the commission decision, we are confident that the Premier League would have suspended Mr Tevez's registration as a West Ham player. We have no doubt that those [Tevez's] services were worth at least three points to West Ham over the season and were what made the difference between West Ham remaining in the Premiership and being relegated at the end of the season."

Griffiths' comments caused astonishment at West Ham — and within the Premier League — because there does not appear to be any documentary evidence to back up the claim. Nevertheless, because of the strength of what he said the two football bodies felt compelled to investigate further. Lawyers will now interview Shear, Joorabchian, Duxbury, West Ham's former chairman Eggert Magnusson, the finance director Nick Igoe and, also, the Sheffield United chairman Kevin McCabe.

West Ham are understood to be confident that they can prove they have committed no further wrong-doing.

In a statement, the two bodies said yesterday: "The joint inquiry will examine whether the conduct of West Ham United immediately after the independent disciplinary commission's decision of 27 April 2007 amounted to further breaches of Premier League or Football Association rules."