Saudi intelligence services have warned of a new al-Qa'ida terror threat against Europe, particularly in France, the French government said.
Interior minister Brice Hortefeux said yesterday the warning of a potential attack by al-Qa'ida in the Arabian Peninsula was received "in the last few hours, few days".
European officials were informed that "al-Qa'ida in the Arabian Peninsula was doubtless active or envisioned being active" on the "European continent, notably France," Mr Hortefeux said during a joint TV and radio interview.
"The threat is real," he said on RTL-LCI-Le Figaro's weekly talk show.
The warning from Saudi Arabia is the latest in a series of alerts that have put French security forces and others in high-vigilance mode.
On September 9, Interpol signalled an "Islamist threat on a world scale, and notably on the European continent", Mr Hortefeux said without elaborating. That was followed by a September 16 report of a woman suicide bomber who could take action in France - later judged not fully credible.
Intelligence sources in North Africa also contacted France about a potential threat as did the US, he said. He said he had spoken at length with US homeland security secretary Janet Napolitano.
It was the first time a French minister has offered details about potential threats since mid-September, when officials first publicly invoked the possibility that France could be a target of radical Islamist groups.
"We must not overestimate the threat or underestimate it," the minister said. "We are directly concerned."
The US State Department advised American citizens living or travelling in Europe earlier this month to take more precautions following reports that terrorists may be plotting attacks on a European city, possibly a shooting spree or other type of attack similar to the deadly 2008 Mumbai attacks in India.
France began boosting security last month at busy tourist sites like Notre Dame Cathedral and the Eiffel Tower, which was twice evacuated after false claims of an attack.
French authorities recorded nine bomb alerts in the capital in September, including the two at the Eiffel Tower - a threefold increase from a year earlier. No explosives were found.
Speculation on the source of a potential terror threat has centred on al-Qa'ida in the Islamic Maghreb, another al Qaida offshoot active in Algeria and Africa's Sahel region, which took five French citizens hostage on September 16 from a heavily guarded mining town in Niger. Two workers from Togo and Madagascar were also captured.
French fears that it could be a target of the Maghreb affiliate of al Qaida are based on Paris' historic ties to the region, where it is a former colonial ruler, and recent enmity caused by measures such as the law banning burqa-style veils in streets.
France also has soldiers in Afghanistan.
A threat from al-Qa'ida in the Arabian Peninsula would be unusual for France and Europe. The group is made up of radical Islamists from Yemen and Saudi branches who merged a year and a half ago.
However, the group has already showed its will to reach beyond the Middle East, claiming responsibility for the failed attempt to down a Detroit-bound jetliner with a suicide bomber in December.
Whether various al-Qa'ida affiliates co-ordinate action or communicate with each other is unknown, but experts tend to doubt that.
Meanwhile, a Yemeni official said yesterday that warplanes bombed al Qaida hideouts in the country's south, killing five militants.
Security measures were tightened around foreign interests and Western embassies in San'a for possible terror acts, a security official said.
Police closed the main road leading to the US embassy and security measures were tightened around the British and the French embassies.
On Friday, the Department of State warned US citizens of the high security threat level in Yemen and France urged families of French workers there to leave the country. Britain has urged its citizens to remain vigilant in Yemen.
On October 6, attackers fired a rocket at a convoy carrying Britain's deputy chief of mission in Yemen, Fionna Gibb, and a separate attack on the same day by a security guard killed a French oil worker. Ms Gibb was unharmed but another embassy official received minor injuries.
The Foreign Office had no comment.