CAIRO, Aug 9 (Reuters) - Five Islamist militants were killed in an explosion south of the Egyptian city of Rafah near the border with Israel on Friday, the state news agency MENA said.

Security sources in Sinai told Reuters that Israel mounted a missile attack on armed Jihadists, killing four, after discovering they had planned to fire rockets into Israel.

They had no information on how the alleged Israeli missiles were delivered.

An Israeli army spokeswoman in Jerusalem declined to comment on the incident.

The Egyptian military said there had been two explosions west of the international border 3 km (two miles) from Al Agra on Friday evening but gave no further details.

Soldiers were searching the area in the North Sinai region to find out more, army spokesman Ahmed Ali said in a statement.

MENA, quoting witnesses, said at least five Jihadists were killed near Rafah. The witnesses said the explosion was the result of the destruction of a launchpad ready to fire rockets into Israel.

Militants based mainly in North Sinai near the border with Israel have escalated attacks on Egyptian security forces and other targets since July 3, when the army deposed Islamist President Mohamed Mursi and installed a new government.

The Egyptian army said on Wednesday it had killed 60 militants in the Sinai Peninsula in the month since then.

The Sinai is largely demilitarized as part of the Israeli-Egyptian peace treaty of 1979 but Israel has approved troop reinforcements to combat the militants and arms smuggling by Palestinians into Gaza. (Reporting by Shadia Nasralla in Cairo, Yusri Mohamed in Sinai and Dan Williams in Jerusalem; Editing by Angus MacSwan)