Cairo: At least 55 Egyptian police and conscripts were killed and six more wounded in a gun battle on Friday during a raid on a suspected militant hideout in the western desert, three security sources said.
Sources had said late on Friday at least 30 police were killed.
Egypt is battling an insurgency concentrated in the Sinai peninsula from two main groups, including an Daesh affiliate, that has killed hundreds of security forces since 2013.
The interior ministry released a statement on the operation on Friday but has so far not given any details on casualties.
At least 23 police officers were killed and the other victims were conscripts, the sources said.
Security sources on Friday said authorities were following a lead to a militant camp in the desert where eight suspected members of Hasm Movement were believed to be hiding.
The group has claimed attacks around Cairo targeting judges and police.
A convoy of four SUVs and one interior ministry vehicle was ambushed from higher ground by militants firing rocket-propelled grenades and detonating explosive devices, one senior security source said.
Militants are mostly fighting in remote northern Sinai where the Ansar Bayt Al-Maqdis group pledged allegiance to Daesh in 2014.
Attacks mostly hit police and armed forces, but militants have also targeted Egypt’s Christians and tourists.
Rocket fire
According to a source close to the security services, the convoy was hit by rocket fire.
There has not yet been a claim of responsibility.
A source told the BBC that said the situation was made worse as the militants were more familiar with the area, while the commanding officer was unable to call for land and air reinforcements due to poor telecommunications in the desert.
Since the army removed President Mohamed Morsi, of the Muslim Brotherhood, extremist groups have increased their attacks on the military and police.
In response to the latest bloodshed Egyptian security forces appeared to step up their operations in the area of the attack.
Two truck drivers heading away from the scene told AFP they had seen heavy deployments of security personnel in the area and that aircraft were carrying out surveillance.
In the face of the latest violence, President Abdel Fattah Al-Sisi on Saturday was sticking to a plan to mark the 75th anniversary of the pivotal victory by the Allies in the World War II Battle of El Alamein at a ceremony involving foreign dignitaries on Egypt's Mediterranean coast, his office told AFP.
But the strongman leader cancelled all his other engagements for the day.
String of attacks
The Muslim Brotherhood, once Egypt's largest opposition movement, has long denied involvement in the attacks on the authorities.
Mohamed Morsi was elected as Egypt's first civilian president in 2012, but the army overthrew him a year later following mass protests against the militants' divisive rule.
Since then, an extensive crackdown on the group has left it in disarray with competing wings that have disagreed on whether to resort to violence, after police bloodily suppressed their protests.
Analysts say a section of the Brotherhood has encouraged armed assaults against the police.
Hasm has claimed multiple attacks since 2016 on police, officials and judges in Cairo.
In their statements, none of the militant groups claim any affiliation to the Muslim Brotherhood.
Hundred of soldiers and police have been killed in the grinding Daesh group insurgency in the Sinai Peninsula in the far northeast of the country.
On October 13, the Egyptian army said six soldiers were killed in a "terrorist" gun and grenade attack on a security post near the North Sinai provincial capital of El-Arish.
Daesh has maintained a steady war of attrition with sniper attacks and roadside bombings.
But unlike their parent organisation in Iraq and Syria, they have been unable to seize population centres in the peninsula, which borders Israel and Gaza.
In October 2015, Daesh claimed the bombing of a Russian airliner carrying holidaymakers home from the popular South Sinai resort of Sharm Al-Shaikh, killing all 224 people on board.