* Sarkozy says doing all he can for hostages in Afghanistan
* No large-scale attacks by Sahara militants
PARIS, July 12 (Reuters) - French President Nicolas Sarkozy said on Monday he was deeply concerned for a French hostage held by al Qaeda’s North African wing, which has threatened to kill him in 15 days unless Paris meets their demands.
The U.S.-based SITE Intelligence Group said on Sunday that Al Qaeda in the Islamic Maghreb (AQIM) had given France 15 days from July 12 to arrange a prisoner exchange and said Sarkozy would be responsible for the life of Michel Germaneau, 78.
“...I have a much more burning worry about another of our compatriots, who is held hostage somewhere in the Sahel. That’s the truth,” Sarkozy said in a live television interview.
He did not say what he intended to do to achieve Germaneau’s release, but in another case involving two French journalists held in Afghanistan, he said the government was negotiating.
“We will do everything, everything, to get them out of the situation they got themselves into,” he said of television journalists Herve Ghesquiere and Stephane Taponier, who have spent 195 days in captivity.
Germaneau is a retired engineer who had worked in the Algerian oil sector. Islamist militants captured him on April 22 in norther Niger, close to the border with Mali and Algeria.
AQIM released a picture and audio of him in May in which he said he had a serious medical condition, and urged Sarkozy to find a “good solution” for him.
Mali, Niger, Algeria and Mauritania have opened a joint military headquarters in southern Algeria.
AQIM killed British captive Edwin Dyer last year after Britain refused to give in to its demands.
It said if Sarkozy did not respond, he would have committed the same “folly” as former British prime minister Gordon Brown.
Governments have little influence in the desert region where he was seized, where bandits, smugglers, former rebels and groups linked to al Qaeda operate.
The militants in the Sahara have so far not staged any large-scale attacks, but Western diplomats say the cash they are accumulating from a series of kidnappings of foreigners will make them a more potent threat.
Western countries say if action is not taken, al Qaeda militants could turn the Sahara into a safe haven along the lines of Somalia or Yemen, and use it to launch attacks. (reporting by Paul Taylor, editing by Tim Pearce)