Hassan al-Turabi has been in and out of jail since he formed his Popular Congress Party.
“Of course I am always against the dictatorship and if I make a statement, I take a strong attitude.”
Armed security agents detained al-Turabi in his Khartoum home in mid-May then launched a dawn raid on his party’s newspaper, Rai Al- Shaab, arresting staff and seizing a print-run.
He spent 45 days in jail and said he had been “isolated completely” during his detention.
In the days prior to his arrest al-Turabi accused al-Bashir of rigging the ballot in the country’s first multi-party elections since 1986, in which parliamentary and state representatives, as well as a president were elected.
The vote itself was marred by complaints from other opposition groups and foreign poll monitors, as well as by accusations of fraud.
Observers from the European Union and the Carter Centre, headed by former US president Jimmy Carter, said after the five days of polling that the election had failed to reach international standards.
Al-Turabi was a former close associate of al-Bashir but has been arrested several times after falling out with him in a bitter power struggle more than 10 years ago.