Shakib said that the two matches, which are part of the World Test Championship, aren't of much value as Bangladesh are at the bottom of the competition's points table. He said that playing in the IPL would rather help him prepare better for the T20 World Cup, to be held in India in October.
"These two Tests are our last matches in the World Test Championship so it is not as if we are going to play the final," Shakib told Cricfrenzy. "We are at the very bottom of the points table. I don't think it makes much of a difference. The other major reason is that the World Cup T20 is in India later this year. It is a very important tournament where we have much to achieve. There isn't much to achieve in these two Tests. I think it is a better option that I prepare myself for something bigger."
Shakib said that his letter to the BCB was focused on his plan to prepare for the T20 World Cup, but Akram Khan, the BCB's cricket operations chairman, said that Shakib doesn't want to play the two Tests against Sri Lanka, to be held from April 21 to May 3.
"Those who keep saying that I don't want to play Tests, I am sure they didn't read my letter. I didn't mention anywhere in my letter to the BCB that I don't want to play Tests. I wrote that I want to play the IPL to prepare myself for the World Cup," Shakib said.
"Akram bhai especially has repeatedly said that I don't want to play Tests. I think he said it again in an interview yesterday. I guess he never read the letter. People should have a clear idea that I wanted to play the IPL even if ODIs were scheduled during this time.
"I want to take advantage of playing in the same grounds and against the same players who I will face in the World Cup T20 four months later. I can share the same experience with my Bangladesh team-mates."
He said that the BCB president Nazmul Hassan's decision to allow him to play in the IPL is laudable. "I want to thank (Nazmul Hassan) Papon bhai for taking the right decision. A player must have the freedom, and his confidence goes up when the board president backs him in this manner. The player becomes more responsible when playing for the national team," he said.
Shakib criticised the BCB's decision to hold the Test series during the IPL. They will also be playing an ODI series against Sri Lanka, possibly from May 20, which will also clash with Shakib's IPL commitment. Shakib said that by doing so, BCB had again given less value to its own cricketers.
"No other cricket board holds international matches during the IPL," he said. "Only we are playing against Sri Lanka. Do you ever see any Afghanistan cricketer playing for their country during the IPL? Their board makes sure the players are free to play in the IPL. If we don't value our own players, how can you expect us to perform well when playing for Bangladesh?
"I will let you in on a brutal truth. When overseas players come to Bangladesh, we call most of them 'sir' or 'hujur', but we do not see our experienced cricketers the same way. If the people, board and players do not respect you, you can't expect them to respect you."
Shakib also criticised the BCB's long-term planning, questioning the role of the High Performance unit, and suggested that some of the BCB directors who have played for Bangladesh in the past haven't done much to progress the game.
"Not having back-up players is really disappointing. I don't know how many players have come from the High Performance squad. We have a number of people in the cricket board who have played for Bangladesh, but apart from (Khaled Mahmud) Sujon bhai, they are not too involved. Sujon bhai and Papon bhai must be credited for the 2020 Under-19 World Cup win.
"But I can't find any more people from the board to give credit. I don't think they think much about cricket (laughs). We hardly talk about these things. Even our journalists are focused on small things. They don't look at the big picture, like how many players we produced in the last five years."
Mohammad Isam is ESPNcricinfo's Bangladesh correspondent. @isam84