* French aircraft bomb Islamist fighters in Mali
* African states speed up plans to deploy troops
* French pilot killed when his helicopter is hit
* Islamist group says French hostages and citizens at risk
By Bate Felix and John Irish
BAMAKO/PARIS, Jan 12 (Reuters) - French aircraft pounded Islamist rebels in Mali for a second day on Saturday and neighbouring West African states sped up their plans to deploy troops in an international campaign to prevent groups linked to al Qaeda expanding their power base.
France, warning that the control of northern Mali by the militants posed a security threat to Europe, intervened dramatically on Friday as heavily armed Islamist fighters swept southwards towards Mali's capital Bamako.
Under cover from French fighter planes and attack helicopters, Malian troops routed a rebel convoy and drove the Islamists out of the strategic central town of Konna, which they had seized on Thursday. A senior army officer in the capital Bamako said more than 100 rebel fighters had been killed.
A French pilot died on Friday when rebels shot down his helicopter near the town of Mopti. Hours after opening one front against al Qaeda-linked Islamists, France mounted a commando raid to try to rescue a French hostage held by al Shabaab militants in Somalia, also allied to al Qaeda, but failed to prevent the hostage being killed.
French President Francois Hollande made clear that France's aim in Mali was to support the West African troop deployment, which is also endorsed by the United Nations, the European Union and the United States.
Western countries in particular fear that Islamists could use Mali as a base for attacks on the West and expand the influence of al Qaeda-linked militants based in Yemen, Somalia and North Africa.
"We've already held back the progress of our adversaries and inflicted heavy losses on them," Hollande said. "Our mission is not over yet."
A resident in the northern city of Gao, one of the Islamists' strongholds, reported scores of rebel fighters were retreating northward in pickup trucks on Saturday.
"The hospital here is overwhelmed with injured and dead," he said, asking not to be identified for fear of reprisals.
In Konna, a shopkeeper reported seeing scores of dead Islamist fighters piled in the streets, as well as the bodies of dozens of uniformed soldiers.
A senior official with Mali's presidency announced on state television that 11 Malian soldiers had been killed in the battle for Konna, with around 60 others injured.
Human Rights Watch said around 10 civilians had died in the violence, including three children who drowned trying to cross a river to safety. It said other children recruited to fight for the Islamists had been injured.
With Paris urging West African nations to send in their troops quickly, Ivory Coast President Alassane Ouattara, chairman of the regional bloc ECOWAS, kick-started a U.N.-mandated operation to deploy some 3,300 African soldiers.
TROOPS BY MONDAY
The mission had not been expected to start until September.
"By Monday at the latest, the troops will be there or will have started to arrive," said Ali Coulibaly, Ivory Coast's African Integration Minister. "Things are accelerating ... The reconquest of the north has already begun."
The multinational force is expected to be led by Nigerian Major-General Shehu Abdulkadir and draw heavily on troops from West Africa's most populous state. Burkina Faso, Niger and Senegal each announced they would send 500 soldiers.
French army chief Edouard Guillaud said France had no plan to chase the Islamists into the north with land troops, and was waiting for ECOWAS forces. France has deployed some special forces units to the central town of Mopti and sent hundreds of soldiers to Bamako in "Operation Serval" - named after an African wildcat.
Concerned about reprisals on French soil, Hollande announced he had instructed Prime Minister Jean-Marc Ayrault to tighten security in public buildings and on public transport in France.
Hollande's intervention in Mali could endanger eight French nationals being held by Islamists in the Sahara. A spokesman for one of Mali's rebel groups, Ansar Dine, said there would be repercussions.
"There are consequences, not only for French hostages, but also for all French citizens, wherever they find themselves in the Muslim world," Sanda Ould Boumama told Reuters. "The hostages are facing death."
The French Defence Ministry said its failed bid on Friday night to rescue a French intelligence officer held hostage in Somalia since 2009 was unrelated to events in Mali.
The ministry said it believed the officer had been killed by his captors along with at least one French commando. But the Harakat Al-Shabaab Al-Mujahideen insurgent group that was holding Denis Allex said he was alive and being held at a location far from the raid.
The French Foreign Ministry stepped up its security alert on Mali and parts of neighbouring Mauritania and Niger on Friday, extending its red alert - the highest level - to include Bamako.
France advised its 6,000 citizens in Mali to leave. Thousands more French live across West Africa, particularly in Senegal and Ivory Coast.
European Union foreign policy chief Catherine Ashton on Friday urged an "accelerated international engagement" and said the bloc would speed up plans to deploy 200 troops to train Malian forces.
A U.S. official said the Pentagon was weighing options such as intelligence-sharing with France and logistics support. French officials suggest U.S. surveillance capacity, including unmanned drones, would prove valuable in vast northern Mali.
In Britain, a spokesman said Prime Minister David Cameron had spoken to Hollande to express support for France's intervention and to offer two C-17 transport planes to assist the mission.
He said both men discussed "the need to work with the Malian government, regional neighbours and international partners to prevent a new terrorist haven developing on Europe's doorstep and to reinvigorate the U.N.-led political process once the rebel advance has been halted".
Military analysts voiced doubt, however, about whether Friday's action was the start of a swift operation to retake northern Mali - a harsh, sparsely populated terrain the size of France - as neither equipment nor ground troops were ready.
"We're not yet at the big intervention," said Mark Schroeder, of the risk and security consultancy Stratfor.
More than two decades of peaceful elections had earned Mali a reputation as a bulwark of democracy - but that image unravelled in a matter of weeks after a military coup last March that paved the way for the Islamist rebellion.
Interim President Dioncounda Traore, under pressure for bolder action from Mali's military, declared a state of emergency on Friday. Traore cancelled a long-planned official trip to Paris on Wednesday because of the violence.
"Every Malian must henceforth consider themselves a soldier," he said on state TV.
On the streets of Bamako, some cars were driving around with French flags draped from the windows to celebrate Paris's intervention.
"It's thanks to France that Mali will emerge from this crisis," said student Mohamed Camera. "This war must end now."