At least six Egyptian security force personnel were killed by a remotely detonated roadside bomb in the Sinai Peninsula on Sunday, medical and security sources said.
The bomb exploded as a patrol responsible for protecting a natural gas pipeline passed by, the sources said.
No group has claimed responsibility for the attack.
The blast occurred southwest of provincial capital Al-Arish where two policemen were killed when their patrol car was struck by a rocket-propelled grenade three days ago.
Security forces face a jihadist insurgency that has killed hundreds of soldiers and policemen since the army toppled Egypt's first freely-elected President Mohamed Morsi of the Muslim Brotherhood last year after mass protests against his rule.
Most attacks occur in the Sinai Peninsula, which borders Israel and the Gaza Strip, as well as near Egypt's Suez Canal.
Security officials say Sinai-based militants are inspired by Islamic State, the al-Qaida offshoot that controls parts of Iraq and Syria and wants to redraw the map of the Middle East.
A senior commander from Ansar Bayt al-Maqdis, Egypt's deadliest jihadist group, has told Reuters that Islamic State has provided instructions on how to operate more effectively.