Francois Hollande
France's President Francois Hollande seen at Elysee Palace in Paris, Jan. 12, 2013 REUTERS

French President Francois Hollande tightened domestic security Saturday as French forces continued to target Islamist militants in northern Mali to force al-Qaeda-linked groups out of their strongholds.

With the support from French forces, Malian government troops routed a rebel convoy and drove the Islamists out of the strategic central town of Konna. The town, some 700 km (400 miles) from the capital Bamako, was captured by the rebels Thursday.

More than 100 rebel fighters had been killed in the offensive, a senior army officer in the capital Bamako told Reuters.

French troops arrived in Bamako Saturday, flying in from bases in Ivory Coast and Chad, Agence France-Presse reported, citing a Malian official. The French contingent is expected to be at full strength by Monday as the first troops promised by African nations join local forces Sunday.

Burkina Faso, Niger and Senegal Saturday pledged 500 troops to join Malian forces.

A French pilot was killed Friday when rebels opened fire at his helicopter near the Malian town of Mopti. Meanwhile, two French soldiers died in a commando raid in Somalia while trying to rescue a French hostage held by al Shabaab militants. The hostage was believed to have died, news reports said.

France’s anti-terrorism alert system known as “Vigipirate” has been reinforced, with security stepped up at around public buildings and transport networks, the BBC reported. Public gatherings are likely to be affected.

The alert will remain red, the second-highest level at which emergency counter-attack measures are put in place.

Hollande, in a television address Friday night, said French forces were fighting alongside Malian government forces, with support from the U.N., the E.U. and the U.S.

"Our action will last however long is necessary," he said. "France will always be ready to defend the rights of a people which wishes to live in freedom and democracy.”

In a statement late Saturday, Mali's interim president Dioncounda Traore said 11 of their soldiers had died and some 60 had been wounded in the fighting.

Fighting between the Malian government forces and the Tuareg rebels broke out in the country’s north in January last year, and the country descended into chaos in March when soldiers toppled President Amadou Toumani Toure in a coup d’état. The security vacuum that followed led to the rebels seizing control of two-thirds of the country. The political instability and fighting have driven 500,000 Malians from their homes, 270,000 of them to neighboring countries.

The Islamists have imposed strict Sharia law, including amputation of limbs as punishment.

Western nations fear that the insurgents, with the support from Al-Qaeda in the Islamic Maghreb, could use Mali as a base for unleashing terror on the West and expand the influence of Islamist militants in Yemen, Somalia and North Africa.