When Fifa president Sepp Blatter and his executive committee arrive in Brazil this weekend for the World Cup finals their concerns will not be confined to the last-minute snag list for this year's tournament, which starts next Thursday. Overshadowing the kick-off to the world's biggest sports event will be allegations that the decision to award the 2022 World Cup to Qatar was secured through illegal payments to former Fifa officials.

Suspicions about the bizarre decision to bring the world's best footballers to a very small country with an inhospitable climate and no football tradition have been widespread since the vote was taken 2011. But the revelations in the Sunday Times that a former Fifa vice-president and a figure close to the Qatari bid, Mohamed bin Hamman, made over €4 million in payments to former Fifa executive members have added significant substance to the belief that the vote for Qatar was questionable, if not corrupt.

In recent months Blatter has been at pains to distance himself from the Qatar decision, conceding that the tournament will have to be played in the cooler winter months and promising that an investigation into the vote by US lawyer Michael Garcia will uncover any illegal practices. That report is due to be published in July but its impact has already been diluted by Garcia indicating that the weekend revelations will not be part of his inquiry.

The unease about Qatar winning the rights to stage the World Cup has been compounded by the inhumane treatment of migrant workers building some of the proposed stadiums. Fifa may win a short reprieve for itself over the course of the next few weeks but the spotlight on the Qatar decision will never be too far away. Even a completely transparent report in July with the promise of a revote on 2022 should not be sufficient to save Blatter and his executive. Only a root and branch clear-out will start the process of restoring confidence in football and its governing body.