The man suspected of attacking soldiers at the Louvre in Paris, named on Saturday as Abdullah Reda Refaie al-Hamahmy, professed support for Isis minutes before the assault, it is claimed.
An Egyptian Interior Ministry official named the attacker as Abdullah Reda Refaie al-Hamahmy, 28, of Egypt but French authorities have not yet confirmed his identity.
The Egyptian official said an initial investigation in Egypt found no record of political activism, criminal activity or membership in any militant group by Mr al-Hamahmy.
French authorities said they are not yet ready to name the suspect, but confirmed on Friday they thought he was Egyptian and had travelled to Paris from Dubai on a tourist visa last month.
Mr Hamahmy reportedly posted on Twitter about a trip from Dubai to Paris on January 26.
In another tweet in Arabic written shortly before the attack, he reportedly posted an angry tirade: "In the name of Allah... for our brothers in Syria and fighters across the world."
He added: "Why are they afraid of the establishment of the Islamic State?” it said. “Because the Islamic State defends its resources and dignity and honor, and respond fight back.”
"No negotiation, no compromise, no letting up, certainly no climb down, relentless war."
According to Paris prosecutor Francois Molins, on arriving in Paris, the suspect bought two military machetes at a gun store.
He also paid 1,700 euros (£1,468) for a one-week stay at an apartment in the chic 8th arrondissement of the French capital, near the Champs-Elysees Avenue.
In an interview with the Dubai-based news channel al-Hadath aired Saturday, Mr Hamahmy's father, Reda Refae al-Hamahmy, said he was shocked to learn of his son's alleged involvement in the latest Paris attack.
"All I want is to know the truth and find out whether he is dead or alive," the father said.
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"This is all a scenario made up by the French government to justify the soldiers opening fire," he added, denying that his son was radical or a member of any militant groups.
"He is a very normal young man," he said.
The suspect's father said Mr Hamahmy is married with a 7-month-old child and told them he intended to tour the sights in Paris before leaving France.
He sent his father a photo of himself with the Eiffel Tower in the background shortly before the clash.
Mr Hamahmy's brother Ahmed, who works at the Health Ministry in Dubai, was interrogated for several hours by security officials in the United Arab Emirates, the father said.
In Egypt, several officers from the domestic security agency visited the family home in the Nile Delta on Friday night to question family members.
