Thousands of civilians fled the Chechen capital yesterday as troops geared up for an assault to drive out separatist rebels controlling most of the city centre. Amid signs of a high-level split over what action to take against the separatist rebels, who stormed the devastated city two weeks ago, Russian national security chief General Alexander Lebed was reported to be preparing for a new peace mission to Chechnya today. The Russian military command earlier announced it would attack the Chechen capital within 48 hours to drive out the rebels. On Monday President Boris Yeltsin gave his security supremo a week to restore order in Grozny and present peace proposals for the Chechen crisis, though yesterday Lebed aides cast doubt over the President's personal role in issuing the order, which forces the general's hand over Chechnya. On Monday General Lebed and Prime Minister Viktor Chernomyrdin restored General Vyacheslav Tikhomirov to the command of Russian forces in Chechnya, ousting General Konstantin Pulikovsky, who had hours earlier ordered civilians out of Grozny as he issued his threat of an imminent all-out attack. The order further undermined a fragile four-day truce, with Chechen rebel commander Aslan Maskhadov urging General Lebed to exert all his influence 'to stop the approaching madness'. General Tikhomirov said he would use all methods, political or military, to oust the rebels from Grozny. Rebel claims yesterday that Russian artillery had killed 100 fleeing civilians were denied by the military. All roads along a corridor opened up for civilians by Russian troops were jammed with people desperate to leave the city of 300,000.