A well-informed source told PTI that the board had handed over the appointment letter to Illyas, who also served on the selection committee and as chief selector in 2011.
"Illyas's appointment was also endorsed by the governing board which met in Lahore on Saturday," he said.
The source said Illyas had asked the board to give him some time to finalise the other members of his committee.
The source disclosed that former Test batsman Basit Ali and former captain Aamir Sohail would also be given key positions this week in the Pakistan cricket set-up.
The source said former Test captain Moin Khan is unlikely to be given an extension as manager of the team for the forthcoming Asia Cup and World T20 in Bangladesh.
"Zaka is not very keen on retaining Moin as manager as he wants to bring in a new management," he said.