West Ham United were last night exploring their legal options with a view to suing the club's former chairman, Terry Brown, for the £5.5 million fine imposed by the Premier League yesterday over the Tevez and Mascherano affair.

An independent disciplinary panel, chaired by Simon Bourne-Arton QC, delivered the biggest financial sanction in English football history, although it did not order a points deduction. West Ham have not yet decided whether to appeal but that would risk the imposition of a points penalty and it is thought a civil action against the old regime is more likely.

The Premiership strugglers were found guilty of acting in bad faith in their dealings with the Premier League, outlawed under rule B13 and leading to a £3 million fine, and of having entered into illegal contracts that allowed a third party to "influence its policies or performance", proscribed under rule U18 and incurring £2.5 million in fines.

It was considered that a points deduction would have been disproportionate because of seven mitigating circumstances, the most notable being the club's guilty pleas and that the finance director, Nick Igoe, had himself brought the illegal agreements governing Javier Mascherano and Carlos Tevez's employment at Upton Park to the attention of the authorities.

Though the judgment stated that "the registration of Tevez can be terminated by the Premier League", that will be avoided if West Ham enter into a loan agreement akin to that drawn up by the companies Global Soccer Agencies and Mystere Services which permitted Mascherano to move to Liverpool in January. There is a deadline of noon today for any new contracts to be lodged with the Premier League.

West Ham's current chairman, Eggert Magnusson, and his advisers were last night meeting representatives of the offshore companies who have controlled the transfer rights to Tevez, MSI Group and Just Sports Inc, which is likely to ensure that the Argentina international striker will be permitted to continue playing for the club for the remainder of the season.

The judgment will not materially affect the Hammers' chances of Premiership survival, and Tevez is expected to feature at Wigan, but the enormous fine was intended to reflect the points deduction the panel was entitled to impose. Also discussed at an internal meeting yesterday was how to pursue Brown, who picked up more than £30 million for the sale of his 36.6 per cent equity in the club.

There was no doubt about how the panel judged the club's misdemeanours under his stewardship: "We are of the view that these are exceedingly serious allegations because they amount to not only an obvious and deliberate breach of the rules but also a grave breach of trust as to the Premier League and its constituent members, because in our finding the club has been responsible for dishonesty and deceit."

The verdict cleared Magnusson of any wrongdoing, and he believes this opens the door to compensation from the previous regime. Brown, Paul Aldridge, the former chief executive, and Scott Duxbury, who remains the executive director responsible for legal affairs at West Ham, were found to have been "anxious to complete the registration of the players by the deadline of August 31st". As a result, Duxbury was put "under considerable pressure from his superiors".

Duxbury, who "surprised" the panel with his assertion that he was not aware of the content of rule U18, breached by the transfers, was found to have misled the league's company secretary, Jane Purdon, in conversations and correspondence leading up to and following the transfer. But it was the conduct of Aldridge, who left the club after the Icelanders' takeover last November, which was most deplored by the panel. It was found he withheld relevant documents from the league even though he had been asked to disclose any such by the Premier League chief executive, Richard Scudamore. Aldridge gave a "categorical assurance there was no such documentation". This, said the judgment, was a "direct lie". Aldridge did not give evidence to the panel and did not respond to calls last night. Guardian Service