India's National Register of Citizens (NRC) is completely an "internal affair", the chief of Border Guards Bangladesh (BGB) Maj Gen Shafeenul Islam said on Sunday (Dec 29).

The BGB will continue to work to prevent illegal crossings into India, its Director General Maj Gen Shafeenul Islam said at a Delhi press conference, reports NDTV.

"This is completely an internal affair of the Indian government," he said when asked to comment on the NRC issue.

Replying to a question on the recent killing of a BSF personnel by a BGB trooper along the border in West Bengal, the BGB DG said it was an "unfortunate, unwarranted and unexpected" incident.

"An inquiry is still on...we will take necessary steps," he said to the Indian media.

BSF DG V KJohri said the incident was unwarranted and unfortunate and that "there are lessons to be learnt."

"We are preparing a detailed standard operating procedure in the wake of this incident that took place along the riverine border along Bangladesh, Johri added.