CAIRO: Egyptian President Abdel-Fattah el-Sissi said in comments published on Saturday that his country's war against Islamic militants in the Sinai Peninsula would be long, but that conditions in the vast and arid region were improving.

In an interview with Egypt's three state-owned newspapers, 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 Islamic State militants attacked an army checkpoint in Sinai, killing 12 soldiers and wounding at least six more.

"The terrorists are evolving and we are improving our operations," he said.

IS claimed responsibility for the attack in a statement Saturday, saying its fighters killed 20 "apostates" and seized all weapons at the checkpoint, located about 80 kilometres (50 miles) east of the Suez Canal, near the town of Bir el-Abd.

The Egyptian military said Friday that troops killed 15 militants in a gun battle at the checkpoint. The IS statement said its fighters had "returned safely" to their base.

Journalists have had virtually no access to northern Sinai in recent years.

Responding to criticism that the military might be distracted by its growing involvement in large civilian infrastructure projects, el-Sissi sought to reassure Egyptians that the armed forces remain committed to their core task.

He said the military's role in the economy would "recede" in coming years, adding: "Rest assured the armed forces are capable and qualified to protect Egypt."

El-Sissi was Egypt's top general when he led the overthrow of Mohammed Morsi, an elected but divisive Islamist president, in 2013. El-Sissi was elected president the following year.