Mohamed bin Hammam, the former president of the Asian Football Confederation who challenged Sepp Blatter for the presidency of Fifa, has had his lifetime ban, imposed in August, annulled by the court of arbitration for sport. However, the judgment was heavily qualified, stressing Bin Hammam had not been found innocent of providing the cash for $40,000 payments, which were handed out by the former Fifa executive committee member Jack Warner to delegates of the Caribbean Football Union, days before the election.

The three-man Cas panel, which included the British QC Philippe Sands, emphasised only that it was "case not proven," because the evidence, compiled following Fifa's own investigation, was not sufficient to definitively prove Bin Hammam provided the suitcase full of dollar bills.

The CAS judgment found by a 2-1 majority, damagingly for Bin Hammam: "It is more likely than not that Mr Bin Hammam was the source of the monies … and that his conduct … may not have complied with the highest ethical standards that should govern the world of football and other sports."

CAS found, though, that the investigation carried out by Fifa, into the allegation that the $40,000 payments came from Bin Hammam, and were bribes to buy the CFU delegates' votes: "Was not complete or comprehensive enough."

Bin Hammam always argued that the Fifa action was mounted against him because he challenged Blatter for the presidency, and that he would be cleared at CAS. The judgment found, however, that he had done nothing to trace the source of the dollars: "It is possible to infer that the failure of Mr Bin Hammam to carry out that relatively simple exercise … might be explained by the fact that it would have confirmed that he was the source."

The exposure of the cash payments, to a gathering of CFU members in Trinidad called to hear a pitch by Bin Hammam for the presidency, led to Bin Hammam withdrawing as a candidate. That left the election clear for Blatter to be the only name on the ballot paper, and be voted four more years as president of football's world governing body. Fifa's ethics committee then banned Bin Hammam from Fifa activities for life, finding he had paid the money as bribes to buy votes, which was upheld by Fifa's appeal committee in September.

Despite the annulment of that ban, Bin Hammam cannot now restart his football activities, because earlier this week, he was provisionally suspended by the AFC, which alleged following an audit that there was evidence of gifts and bribery during his period as AFC president.

Following the Cas judgment, Fifa issued an immediate statement promising another investigation into Bin Hammam. Stressing that "Mohamed Bin Hammam has not been proven innocent", Fifa promised to pass "all relevant files" to its newly-reconstituted ethics committee, to decide if "any action is required to be taken" against Bin Hammam.

The ethics committee, with its new chairman, the American attorney Michael Garcia, is also to examine the ISL scandal, in which CHF41m (£26.7m) bribes were paid to the ex-Fifa president Jaoa Havelange, and former president of the Brazilian football federation Ricardo Teixeira, with Blatter's knowledge. Blatter, responding to calls for him to resign, has insisted he did nothing wrong.