Prince Harry has acknowledged killing 25 people in Afghanistan during his time as an Apache helicopter pilot, according to the United Kingdom’s media, quoting a soon-to-be-published autobiography, writes Al Jazeera.

Harry, the duke of Sussex, served in Afghanistan first as a forward air controller in air raids from 2007-2008, then flying the attack helicopter between 2012-2013.

The 38-year-old is due to release a book, Spare, in the next week, in which he revealed that he undertook six missions as a pilot that led to him “taking human lives”, the Daily Telegraph reported.

Harry said he was neither proud nor ashamed of doing so. He also described eliminating the targets as like removing “chess pieces” from a board.

“My number is 25. It’s not a number that fills me with satisfaction, but nor does it embarrass me”, - he wrote.

Video cameras mounted on the nose of his Apache helicopter enabled him to assess his missions – and determine with certainty how many he had killed.

The prince explained his justification for his actions because of the 9/11 attacks in the United States and meeting families of the victims.