(Adds government spokesman, MNJ warning to uranium miners) By Abdoulaye Massalatchi NIAMEY, Nov 23 (Reuters) - Niger's President Mamadou Tandja on Friday prolonged a state of alert in the desert north, home to some of the world's largest uranium reserves, where security forces have been battling a uprising led by Tuareg nomads. The move extended for a further three months extra powers of arrest given to the security forces in August and followed a warning from the government that the rebel Niger Movement for Justice (MNJ) planned to widen its 9-month-old campaign. "The state of alert declared in the region of Agadez is extended for three months from November 24, 2007," Tandja said in a decree broadcast on state radio on Friday. The MNJ has killed at least 46 soldiers and taken dozens hostage since launching a revolt in February to demand more autonomy and a greater share of mining revenues. The unrest has threatened to disrupt activities by firms including French nuclear group Areva <CEPFi.PA>, whose uranium production in Niger has fuelled France's nuclear industry for decades, and Sino-U, a unit of China's state-run nuclear firm which is preparing to start production in Niger. Communication Minister Mohamed Ben Omar said in a statement broadcast on national television late on Thursday that the security forces had chased elements of the MNJ out of the Agadez region and into neighbouring countries. But he said that an attempt, foiled by the army on Wednesday night, to blow up a fuel depot in the western town of Dosso -- just 140 km (90 miles) east of the capital Niamey -- showed that the rebels wanted to widen their campaign. "This act ... proves that the MNJ and its supporters are changing their tactics and sharpening their strategy with the aim of carrying out acts of urban terrorism," Ben Omar said. He warned that the group appeared to be attempting to bring "violence and terror" to Niger's towns and urged the population to be vigilant and to report any suspicious acts. WARNING TO URANIUM MINERS Some diplomats say a purely military strategy to combat the insurgency risks worsening the problem. They point out that a heavy-handed clampdown by the security forces involving the arbitrary arrest and detention of Tuaregs triggered a full-scale rebellion in the north in the early 1990s. The light-skinned tribesmen, fighting for greater autonomy from a black-African dominated government, signed a peace deal in 1995 but the MNJ says the terms of the deal have never been fully implemented and that the region remains marginalised. The group has threatened to disrupt uranium mining in the north until local people benefit from the industry and renewed its threat against Areva and other mining firms on Friday in response to Tandja's decree. "All traffic on the uranium route is forbidden. Any truck which takes it will do so at its own risk. The MNJ will no longer allow Areva and Tandja to decide the fate of Niger's people," it said on its Website, m-n-j.blogspot.com. Ben Omar said the MNJ's changing tactics were a reaction to the security forces' success in chasing its leaders out of their bases in northern Niger. "Most of the armed men have fled due to the military pressure on them and they are no longer on our territory," said a senior military officer in Niamey, asking not to be named. Niger's remote north is bordered by Mali, Algeria and Libya. "What we want now is for the (neighbouring) countries concerned about organised crime to co-operate by tracking them and neutralising them," he said. (Writing by Nick Tattersall, Editing by Pascal Fletcher)
