CAIRO, Aug 9 (Reuters) - Four Islamist militants were killed by a missile strike in Egypt's North Sinai region on Friday as they prepared to launch rockets at Israel, Egyptian security sources said.
Five security sources told Reuters the attack was carried out by Israel. But the Egyptian armed forces officially denied that was the case and an Israeli army spokeswoman in Jerusalem declined to comment on the incident.
The two countries have cooperated in tackling the threat from Islamist militants in Sinai in the past and this case appeared unlikely to provoke a diplomatic row.
The Egyptian military said two explosions took place at a site 3 km (two miles) west of the border and south of the city of Rafah on Friday afternoon. Soldiers and specialist teams were searching the area to find out more, army spokesman Ahmed Ali said in a statement.
The security sources in Sinai told Reuters that an Israeli aircraft struck at the armed Jihadists, killing four, after discovering they had planned to fire rockets into Israel.
One source said that the Israeli aircraft had observed the militants preparing three rocket launchpads to hit Israel. It launched a missile, killing two men, then killed another pair who stepped up to the pads after the first strike.
However, an Egyptian army spokesman denied in a subsequent statement any Israeli role in the incident.
BORDER IS "RED LINE"
"It is not true, either in form nor substance, that there were any attacks from the Israeli side inside Egyptian territory," he said.
"Likewise, the claim that there exists coordination between the Egyptian and the Israeli side in this matter is a matter completely void of truth."
The Egyptian border was a red line that could not be violated, he said.
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.
Militants based mainly in North Sinai near the border 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.
Israel took the rare step of shutting its southernmost Eilat airport near the Sinai peninsula for two hours on Thursday citing security concerns.
The desert peninsula has long been a security headache for Egypt and its neighbours. Large and empty, it also borders the Palestinian-ruled Gaza Strip and flanks the Suez Canal linking Asia to Europe. It is also home to nomad clans disaffected with rule from Cairo. (Reporting by Shadia Nasralla and Yasmine Saleh in Cairo, Yusri Mohamed in Sinai and Dan Williams in Jerusalem; Writing by Angus MacSwan; Editing by Andrew Roche)