(Adds ******r killed in separate attack on Sunday) CAIRO, April 19 (Reuters) - The Egyptian militant group, Ajnad Misr, claimed responsibility on Saturday for a blast that killed one police ******r in Cairo. The bomb exploded in Cairo's Leba**n Square on Friday night, killing the ******r and wounding a**ther. Ajnad Misr, or Soldiers of Egypt, said in a statement on an Islamist website that its militants had monitored a police checkpoint in the square before detonating the bomb. It has claimed at least six attacks since then, including explosions outside Cairo University which killed a police brigadier-general and one other person earlier this month.