"They wanted me to betray the principles of my job and to turn me into a spy.
"It was made clear to me later the main goal behind my detention was to detain the journalist who reveals the truth.
"They did not want to shed any light on their horrible crimes in Afghanistan."
Al-Hajj was released early on Friday and flown from Guantanamo Bay prison in Cuba to Khartoum, after being imprisoned for nearly six and a half years without charge or trial.
Al-Hajj also said that he was subjected to harsh psychological and physiological torture.
He said that the psychological torture included guards insulting the Quran and on the physiological level he was beaten and force fed.
A US defence department official had accused al-Hajj of faking a poor state of health when arriving in Sudan on Friday.
The official said on ABC news that al-Hajj was a "manipulator and a propagandist".
Al-Hajj's credibility was doubted by the official who said that there was "no information to substantiate his allegations that he was mistreated at Guantanamo".
Guantanamo Bay has been run by the US as a detention centre for "enemy combatants" and those considered a security threat since 2002.
It is part of the US' "war on terror".
Although more than 500 prisoners have been released from the camp, 250 people remain.