Arrested Hamja Khan is an assistant secretary of district unit BCL.
Police arrested Hamja from his residence in Manikganj town and sent him to jail.
Religious affairs secretary of Ghior upazila Jubo League on 13 June filed a case against Hamja and two others under the Digital Security Act, he added.
Jubo League is the youth front of ruling AL.
They served Hamja a show cause notice in this regard but he did not reply, Raju said.
Organisational steps would be taken against Hamja after informing the matter to the central committee, the BCL president added.