CAIRO (AFP) - Egypt's public prosecutor has launched an investigation into a journalist well-known for his campaigns against Islamists, after he questioned a miracle that clerics say was carried out by the Prophet Mohammed.

Ibrahim Issa - an ardent critic of the Muslim Brotherhood group, outlawed by the regime of President Abdel Fattah al-Sissi - made the comments on Friday during a show he presents on a private television channel.

Issa claimed that the "Israa and Miraj", the mystical night journey of the Prophet Mohammed from Mecca to Jerusalem, from where he ascended to the heavens, was "a completely delusional story".

He said Muslim preachers who only cite books that confirm the event - and ignore others that deny it happened - as being "Salafist views", and that he claimed failed to offer a wider understanding of Islam.

Egypt's highest theological authority, Dar al-Ifta, issued a seven-point response Saturday stating the Israa and Miraj journey "definitely happened, and cannot be denied in any way." On Saturday, Egypt's public prosecutor ordered "investigation measures" into Issa.

Egypt's Supreme Council for Media Regulation also said it will prepare a report "to take legal action in case of violation" of its codes.

Issa's comments sparked wide controversy on social media, including by both critics and supporters, while Egyptian actor Mostafa Darwish quit filming a movie authored by Issa called "The Atheist".

One Twitter user condemned Issa for casting doubt on Islamic teachings, while another praised him for helping a "national project for modernisation and revolution against the fanatics." In November, Issa sparked controversy after saying he was surprised to find a pharmacist reading the Koran in a pharmacy.

"Reading the Koran is a beautiful thing ... but you should prioritise reading a book on medicine," Issa said then.

Issa was also an outspoken critic under the three-decade rule of Hosni Mubarak, who was toppled in 2011 following mass protests.