Egypt's military said on Tuesday it has killed 38 militants and arrested more than 500 jihadists and suspects, days after launching a major operation against the Islamic State group affiliates in Sinai.

The military said it had killed 10 "extremely dangerous" extremists, in addition to 28 jihadists it had previously announced as having been killed.

A statement added that 400 "criminal elements and suspects" had been arrested, having previously announced the arrest of 126 people.

The Egypt military spokesperson Colonel Tamer al-Rifai, said the dead jihadists had been "hiding inside a house, in the vicinity of the North Sinai capita El-Arish city following a shoot-out.

On Friday last week, the Egypt military announced the start of their "Operation Sinai 2018" in the Sinai Peninsula, bordering Israel, the central Nile Delta and the Western Desert near the border with Libya.

The security sweep comes as President Abdel Fattah al-Sisi seeks re-election in March, after a first term in office that has seen him crack down on an Islamist insurgency and other opponents.