The French government is strengthening internal security in the country as its forces are stepping up their offensive against al-Qaida-linked Islamist rebels in Mali.
French President Francois Hollande has ordered the country's security agencies to step up vigilance at public places over the escalating situation in Mali and Somalia.
The anti-terrorism alert system known as "Vigipirate"' in France is also coming into force to beef up security for government buildings and the public transport system.
The "struggle against terrorism" has forced France to flag the second-highest level of emergency counter-attack measures, said Hollande. There is growing fear that Islamist extremists could launch retaliatory attacks on French targets.
French aircraft are pounding the Islamist rebels in the landlocked Mali for a second day.
Fighter planes and attack helicopters are striking at Islamist rebel positions and the militants have been driven out of the key town of Konna. Hundreds of French troops have also been deployed in Konna and in the capital Bamako.
Around 6,000 French expatriates living in the capital have been advised to leave the country.
Making his intentions clear, Hollande said: "We've already held back the progress of our adversaries and inflicted heavy losses on them. Our mission is not over yet." The rebels have also shot down a helicopter killing a French pilot.
French hostage, Denis Allex, held by the al-Qaida-linked Shabaab militants in Somalia since July 2009 was killed after a failed operation by French troops.
"There are consequences, not only for French hostages, but also for all French citizens, wherever they find themselves in the Muslim world. The hostages are facing death," a rebel group Ansar Dine's spokesperson, Sanda Ould told Reuters.
Nearly a dozen Malian soldiers have been killed in the conflict and scores of others have been injured. Reports of civilian casualties have also emerged as Human Rights Watch says ten people have been killed in Konna.
Hollande has defended the intervention, claiming international legal sanction, as the UN had recently approved deployment of troops by West African nations to recapture Northern Mali.
France had also sought deployment of troops, which was not expected until September due to logistical reasons.
The West African bloc Ecowas has dramatically quickened the process. "By Monday at the latest, the troops will be there or will have started to arrive. Things are accelerating ... The reconquest of the north has already begun," said Ivory Coast President and Chairman of Ecowas, Alassane Ouattara.
The 3,300-strong troops will be drawn from Nigeria, Burkina Faso, Niger and Senegal.