Islamic State terrorists are gearing up to bomb large crowds during next month's Euro 2016 soccer championships, a French spy chief has warned.
However, Irish fans last night vowed to travel to Paris, Bordeaux and Lille to support the Boys in Green - despite the alarming warning from the intelligence agency.
Patrick Calvar, head of France's DGSI internal intelligence agency, made the rare security remarks during a briefing to the French government.
Mr Calvar told the French parliament's defence committee that Islamic State (IS) was planning attacks on large crowds of people.
He said that "a new form of attack … characterised by placing explosive devices in places where there are large crowds and repeating this type of action to create a climate of maximum panic" should be expected.
"Clearly, France is the most threatened and we know that Daesh (IS) is planning new attacks," Calvar told the committee on May 10, according to a transcript of his testimony released to the media yesterday.
His comments came as investigations into how EgyptAir flight MS804 crashed yesterday, just three-and-a-half hours after taking off from Charles de Gaulle Airport in Paris.
Security levels remain high in Paris six months after IS militants killed 130 people in coordinated assaults on cafes, bars, the national stadium and a music hall across Paris. He said the militant group had the numbers to launch new attacks, including some 645 French citizens or residents currently in Syria or Iraq, of which 400 were fighters. A further 201 were either in transit to or from the region, he said.
Euro 2016 starts on June 10 and runs for a month at 10 stadiums across France. Over 2.5 million spectators are expected for 51 soccer matches involving 24 nations.
There will also be fan zones for crowds watching games on big screens in major cities.
Irish supporters last night said they would not be put off from travelling to Paris - despite the worrying remarks made by the French intelligent agent. The FAI Believe supporters club said the warning would not stop fans from travelling.
Instead, chairman Andrew Whelan said that supporters would be conscious of the warnings in "the background".
"It's not going to stop us. If you live your life worrying about that, you are letting them win. That's what terrorism feeds off," Mr Whelan told the Herald last night.
"It is what it is. It can happen, you can go to Lanzarote on holidays and it could happen. I can't see why they would attack an Ireland game. I'd say the security will be so tight.
"Personally, I'm going on a family holiday. We are staying an hour outside Paris and will travel in and out of the games."
Meanwhile, the You Boys in Green (YBIG) supporters club say the majority of its members would travel to support Martin O'Neill's side.
Club spokesman Ger Keville said that 95pc of members indicated in a recent poll that terrorism threats would not stop them from travelling.
"The general feeling is that although people will be wary, they are not worried," he told the Herald.
"People are thinking that there is nothing they can do about the security aspects, let's go and support the team.
"I don't think people are being heroes about this, it's just you can't live your life in fear either," Mr Keville added.
Irish pubs in Paris are also urging supporters to continue their travel plans. Kandic Kalwoda, a manager at O'Sullivans Irish Bar in Paris, said the atmosphere was building ahead of the Euro championships.
"We have no concerns in O'Sullivans," said Ms Kalwoda.
"We cannot give in to terrorists. We look forward to welcoming Irish fans to Paris."
Meanwhile, the Department of Foreign Affairs last night said they were engaged in "intensive planning and preparations" for the Euros with Uefa, the FAI, gardai, the Irish travel industry and French authorities.
"The Department is making available extra staff, extra resources and specialised training both on the ground in France and at HQ in Dublin to assist with the consular effort," a spokesman told the Herald.
"Irish fans are advised to act responsibly and to respect and follow local security authority advice and the heightened security measures that will be in place," the department said.