Fifa presidential candidate Sheikh Salman bin Ebrahim al-Khalifa has called allegations he was complicit in the torture of footballers "nasty lies".
Sheikh Salman has been accused by Bahraini human rights groups of helping to identify players and other athletes involved in 2011 democracy protests.
He was head of the Bahrain Football Association and a member of the ruling royal family when security forces put down mass Shia-led protests calling for political reforms.
Several people died, while others were arrested, detained and tortured.
"I cannot deny something that I haven't done," the 49-year-old told BBC Sport.
"Such accusations are not just damaging, it's really hurting. Some people have agenda on their table."
Sheikh Salman added: "It's not just damaging me, it's damaging the people and the country.
"These are false, nasty lies that have been repeated again and again in the past and the present."
Applications to succeed Sepp Blatter as president of football's world governing body had to be submitted by 23:00 GMT on Monday.
Nic McGeehan of Human Rights Watch, told BBC Radio 5 live: "Everyone concerned with football should be extremely concerned that a member of the royal family of Bahrain is up for this post.
"This is a royal family that conducted a brutal crackdown in 2011, when security forces shot unarmed people dead in the street and tortured five people to death in custody.
"First of all it is not our role to decide who should or shouldn't be head of Fifa. These are the facts of the matter - people were tortured to death in Bahrain by the ruling family and security forces. There are clear issues about in Sheikh Salman's role in 2011.
"We are going to put the facts out there and people can decide for themselves if this man is fit to lead Fifa. The facts speak loud and clear to why this would be a very dubious choice. This is a lot worse than bungs and brown envelopes."
In an interview with the BBC's Richard Conway, Salman said:
- he will not take a salary if he is elected president of Fifa
- he backs the 2018 and 2022 World Cups to go ahead in Russia and Qatar respectively
- accusations of human rights abuses are false and "damage Bahrain"
- he supports limiting the Fifa presidency to three terms and 12 years
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President of the Asian Football Confederation since 2013, Sheikh Salman vowed to clean up Fifa's reputation, which has been left in tatters following a much-publicised spate of corruption charges, which began in May when seven top officials were arrested in Zurich.
"With the support I'm going to get we're going to turn it around very quick," he said. "We have big examples of football organisations around the world - the Premier League, the Bundesliga, even Uefa - who have, from a football side and a revenue side. And this is what we want to bring to Fifa."
With seven other candidates thought to be in the running for the Fifa presidency, Salman added: "To the other candidates, they have to be realistic as well.
"Unless you are supported by your confederation it's going to be a very difficult job."