The BCB banned Ashraful while he was being investigated by the International Cricket Council anti-corruption and security unit.
Ashraful said on Tuesday he told the investigators he was involved in wrongdoing.
"I've acknowledged my mistakes to the investigators," Ashraful said in Dhaka. "I apologize to my fans."
The allegations relate to two matches Ashraful's team, Dhaka Gladiators, played and lost against Chittagong Kings and Barisal Burners in February. Ashraful captained Dhaka to the BPL trophy.
BCB President Nazmul Hassan Pappon didn't elaborate on the charges, and said the ICC will submit a report within a week.
Ashraful, still playing for Bangladesh, was captain from 2007-09.