The leader of Islamic State (IS) in Egypt has warned Muslims to stay away from Christian gatherings as well as government, military and police facilities, suggesting that the militant group will keep up attacks on what he referred to as "legitimate targets", according to agency reports.

"We are warning you to stay away from Christian gatherings, as well as the gatherings of the army and the police, and the areas that have political government facilities," the leader, who was not named, said in an interview in IS's Al Naba weekly newspaper published on Telegram and quoted by Reuters.

IS militants are increasingly targeting religious minorities, a challenge to President Abdel Fattah al-Sisi, who came to power promising to crack down on extremists.

And according to reports, groups affiliated with IS have begun enforcing their own strict version of Islam in North Sinai.

Attacks go beyond Sinai

The warning comes as Egypt remains on high alert one month after two IS suicide bombers killed more than 40 people at churches in Alexandria and Tanta.

Sisi announced a three-month state of emergency following the twin church bombings, the deadliest attacks on Egypt’s Coptic Christian minority in recent memory.

Also last month, IS claimed responsibility for an attempted attack at a checkpoint near the ancient St Catherine’s monastery in Sinai which left one policeman dead.

Cairo has been fighting a long-running insurgency by a local affiliate of IS in the province of North Sinai since 2014, when Ansar Bayt al-Maqdis pledged allegiance to the group.

Targeting worshippers and religious sites both inside and outside Sinai marks a significant change of tactic: previously the group had mostly attacked police, soldiers and their informants.

In response, the authorities have smashed a network of tunnels used to smuggle weapons in from Gaza, razed hundreds of homes to create a no-man's land, and mounted numerous air strikes. Those policies have prevented militants seizing territory - but have come at a high cost for locals.

Threat comes after visit

In a visit to Egypt last week, Pope Francis appealed for dialogue to battle extremism as he addressed thousands of faithful during a visit to promote reconciliation with Muslims and support its embattled Christians.

Please pray for my journey tomorrow as a pilgrim of peace to Egypt. — Pope Francis (@Pontifex) April 27, 2017

"The only fanaticism believers can have is that of charity," the pope said at a mass for Egypt's Catholics.

"True faith... moves our heart to love everyone... It makes us see the other not as an enemy to be overcome but a brother and sister to be loved," he told a crowd of about 15,000 pilgrims. "It spurs us on to spread, defend and live out the culture of encounter, dialogue, respect and fraternity." The pope also visited a Coptic church bombed by IS in December.

isis bombed this church in Tanta, Egypt a week ago and look how many people still attended the next week #WeAreNotScared #ProudToBeCoptic pic.twitter.com/cAAWqpFgkv — ChampagneJuJu (@jhabashy15) April 16, 2017

The spiritual leader of the world's almost 1.3 billion Catholics also became the first pope to visit the headquarters of the grand imam of Al-Azhar, Ahmed al-Tayeb, one of the Muslim world's leading religious authorities.