Twenty-six Egyptian soldiers were killed or wounded on Friday in attacks on checkpoints in the Sinai Peninsula where the Islamic State group is conducting an insurgency, the military said.
Security officials who requested anonymity said at least seven soldiers were killed, but it was not immediately possible to obtain an official death toll.
The military said it killed 40 assailants as it clashed with extremists in North Sinai, the main focus of the deadly IS insurgency.
Security officials said ambulances raced to the sites of the attacks south of the town of Rafah on the border with the Gaza Strip.
Jihadists have killed hundreds of policemen and soldiers in attacks in North Sinai since the military toppled Islamist president Mohamed Morsi in 2013 and launched a deadly crackdown on his supporters.
North of Cairo, two gunmen shot dead an officer with the police's National Security service on Friday as he left his home, the interior ministry said in a statement.
While IS has claimed attacks outside Sinai, a number of lesser known groups have also conducted bombings and assassinations in the capital and the Nile Delta.
IS has also attacked tourists, killing all 224 on board a Russian plane carrying holidaymakers in 2015, as well as Christian churches elsewhere in Egypt.
The jihadists in the Sinai pledged allegiance to the Islamic State group in late 2014, establishing the self styled "Sinai Province" on the peninsula, which borders Israel as well as Gaza.
Unlike their main organisation in Syria and Iraq, they have been unable to seize population centres, with one attempt to occupy a town in 2015 ending with the military unleashing F-16 jets against the jihadists.
Instead the group has tried to keep up a steady war of attrition involving roadside bombings, sniper fire and checkpoint attacks such as the ones on Friday.
The jihadists are increasingly encircled on the peninsula, with the military razing sections of Rafah to create a buffer zone with the Gaza Strip and destroying tunnels connecting with the Palestinian territory.
But that has failed to prevent them from establishing cells elsewhere in Egypt that launched a series of attacks on Christians that have killed dozens since December, when a suicide bomber targeted a Cairo church.
That attack was followed by two church bombings in April that killed at least 45 people and a massacre of Christians heading on a bus to a monastery in May.
The April attacks prompted President Abdel Fattah al-Sisi to declare a nationwide state of emergency like that already in force in North Sinai.
Sisi, who as army chief toppled Morsi, has pledged to defeat the jihadists.
The military has killed several of their commanders, including their top leader Abu Duaa al-Ansari in 2016.