France is braced for a 9/11-style attack or a missile strike on a passenger plane, intelligence sources claimed today.

Security forces and the army are reportedly readying for more violence on a far larger scale after a series of terror attacks in the country.

President François Hollande has also warned of the inevitable threat by Islamist insurgents after a jihadi gunman was thwarted while storming a high-speed train on Friday.

French security security services have warned that France be targeted with a 9/11-style attack or a strike on a passenger jet with a surface-to-air missile (like the one above) after a series of terror attacks in the country

Agents of the DGSI, France's equivalent of MI5, said the country could be targeted by an attack on the scale of the Twin Towers atrocity in 2001.

A source told the Le Canard Enchaîné newspaper that there were fears of 'an upcoming 11 September à la Française where intelligence services are mere spectators'.

Another intelligence source warned a passenger jet could be targeted by a surface-to-air missile.

They told The Daily Telegraph: 'Airlines have been warned of a possible attack on a plane with an anti-tank missile. But pilots are unsure how to take evasive action.'

Suspect: Ayoub El-Khazzani (above), 26, has denied accusations that he was trying to carry out a terrorist attack on Friday. The prosecutor dismissed his robbery story as a 'complete fantasy'

Three Americans and British businessmen Chris Norman then stepped in to overpower the attacker (above)

The army has made plans to wrest back control of districts where there are 'a lot of alienated and angry fourth-generation immigrant kids' and weapons are easily available, the source said.

'The prospect of radicalisation is increasingly likely,' they added.

'We're dealing with highly-organised networks of militant Islamists embarked on a campaign of violence and determined to intensify it.'

Some of these drug-infested suburbs are near the main Paris airport at Roissy, raising fears a plane could be targeted as it was taking off or landing.

It is also believed that a number of rocket-propelled grenades and missiles were smuggled into the country after the fall of Libyan dictator Colonel Gaddafi.

Heroes: Four train passengers (l-r) British businessman Chris Norman, US student Anthony Sadler, US Airman Spencer Stone and US National Guardsman Alek Skarlatos pose with French President Francoise Hollade after been awarded France's highest honour for bravery for tackling a gunman on a high-speed train

France has admitted to sending 'light weapons' to Libyan rebels in 2011 and French media claim heavier weaponry like European-made Milan anti-tank ballistics were also delivered.

The warnings come after Moroccan gunman Ayoub El-Khazzani was overpowered by three Americans and a British grandfather while trying to launch an attack on an Amsterdam to Paris train last week.

Earlier this week, it emerged that Khazzani had watched a video of 'Islamic preaching' which encouraged 'violent acts' shortly before he was foiled.

Paris' most senior prosecutor Francois Molins also dismissed Ayoub El-Khazzani claims that he had planned to carry out a robbery after finding some guns and ammunition as a 'complete fantasy'.