It is still not clear why Shakib applied for leave after the team was announced.
Before the all-rounder submitted his letter, BCB President Nazmul Hassan told the media that Shakib asked for a leave verbally, "but he has to apply for it officially and show valid reasons."
Within a few hours after that, Shakib sent a letter to the BCB.
The all-rounder is now playing in the Dhaka Test against Pakistan. He missed the first match of the series due to a hamstring injury.
Bangladesh team is scheduled to leave for New Zealand on 9 December. The first Test of the series will start on 1 January, and the second on 9 January.