Egyptian President Abdel-Fattah el-Sissi says the war against Islamic militants in the Sinai Peninsula will be long, but that conditions in the vast and arid region were improving.

Speaking in an interview with Egypt's three state-owned newspapers published Saturday, he acknowledged that both the militants and government forces were getting better at fighting each other in the strategic area bordering Israel and the Hamas-ruled Gaza Strip.

"Conditions in Sinai are improving and (our) efforts are continuing because the war is long," said el-Sissi, whose comments came one day after militants from the extremist Islamic State group attacked an army checkpoint in Sinai, killing 12 soldiers and wounding at least six more.

IS claimed responsibility for the attack in a statement Saturday, saying its fighters killed 20 "apostates" and seized weapons.