Pope Francis has expressed his sorrow and offered prayers for a "savage attack" in at a church in the French city of Nice in which three people were killed in a knife attack described as a "terrorist incident" and which was denounced by the French president.

The attack took place in the Basilica of Notre Dame on Oct. 29 in which an elederly person's throat was slit.

It occurred in the city of on the Mediterranean coast during a time of mounting heightened tensions in France over radical Islamism, secularism and freedom of speech.

President Emmanuel Macron denounced the "Islamist terrorist attack" at the Notre-Dame basilica after visiting the scene in the southern city, the BBC reported.

World Council of Churches interim general secretary Rev. Ioan Sauca expressed solidarity with the churches and people of France, and condolences to the families of the victims,

"Following the horrific killing of teacher Samuel Paty earlier this month, these atrocities demand a renewed search for an effective response to the phenomenon of violent religious extremism, not only in France, but in the many countries around the world that continue to be afflicted by it each day."

"There can be no legitimate religious justification for this brutality, and any and all attempts to justify such attacks on religious grounds must be categorically denounced."

One elderly victim who was praying was "virtually beheaded". Another woman and a man also died. A suspect was shot and detained shortly afterwards.

The sexton, a lay member of staff responsible for the upkeep of the church, aged in his late 40s or early 50s and with two children had his throat cut while preparing for morning mass, said Gil Florini, a Catholic priest in Nice, Reuters news agency reported.

MAN BEHEADED

The main beheaded an elderly woman, and badly wounded a third woman, according to a police source.

The attack came just weeks after Samuel Paty, a high school teacher, was beheaded in a terrorist attack in Paris.

Two other attacks were carried ou on the same day in France and Saudi Arabia.

A man was shot dead in Montfavet near the southern French city of Avignon after threatening police with a handgun.

Separately, a guard was attacked outside the French consulate in Jeddah in Saudi Arabia. A suspect was arrested and the guard taken to hospital.

"Informed of the savage attack that was perpetrated this morning in a church in Nice, causing the death of several innocent people, His Holiness Pope Francis joins in prayer with the suffering of the families who were affected and shares their sorrow," the pontiff said in a message to Bishop André Marceau of Nice.

"Condemning such violent acts of terror in the strongest possible way, he assures the Catholic Community of France and all the French people of his closeness and he calls for unity," said the message.

Nice Mayor Christian Estrosi spoke of "Islamo-fascism" and said the suspect had "repeated endlessly 'Allahu Akbar' (God is greatest)."

Police did not initially impute a motive for the NIce attack. 

It followeed days of protests in some Muslim-majority countries triggered by President Macron's defence of the publication of cartoons that depicted the Prophet Mohammed which in turn trigged calls in some countries for a boycott of French goods.

Four years ago Nice was wracked by another terror attack, on the Frnech national dday on July 14 when a Tunisian man drove ploughed his struck into crowds, killing 86 people.