"We invited Adamu after he finally arrived in the country on Friday and he has been at our office in Abuja since Wednesday morning," disclosed the Economic and Financial Crimes Commission (EFCC) spookesman, Femi Babafemi.
"For now, the investigations are on and we do not know when he will be allowed to leave our offices."
Babafemi said that the anti-corruption body is interrogating Adamu over how the 24 billion naira (about 190 million dollars) budget for the 2003 All Africa Games of which he was the chief executive was spent.
Adamu will also have to explain another 1.3 billion naira, which he purportedly spent as "PR", Babafemi added.
He also said Adamu is being quizzed for another 180 million naira in an affair concerning his wife as well as 80 million naira expenditure involving his son-in-law.
Last month, Adamu was suspended by FIFA for three years after world football's governing body ruled that he had breached their code of ethics.
Adamu was caught in a sting operation by a British newspaper over the hosting rights bids for the 2018 and 2022 World Cups.