BEIRUT — Syrian President Bashar Al-Assad's close aides are considering deserting him as the uprising against the regime shows no signs of abating. On Friday, two brigadier generals and two colonels defected to the opposition camp, Britain-based Syrian Observatory for Human Rights said. A video provided by the observatory showed the four senior army officers announcing their defection. The group said the defections came Thursday — the same day a Syria fighter pilot flew his MiG-21 warplane to neighboring Jordan, where he was given asylum. Thousands of soldiers have abandoned the regime, but most are low-level conscripts. The Free Syria Army, the loosely linked group of rebel forces, is made up partly of Syrian army defectors. Also Friday, Syria's state-run news agency said “terrorist groups" killed and mutilated several people in the northern Aleppo province. The Syrian government refers to rebels as terrorists. Top US officials also hinted that many senior Assad regime advisers have secret plans to defect. Senior military figures who are part of President Assad's inner circle are among those understood to be preparing “exit strategies" if the regime becomes critically threatened by the opposition fighters, the US officials told the British newspaper The Daily Telegraph. The close Assad advisers are establishing lines of communication with opposition leaders to discuss how they would be received if they deserted, the officials said. The aides are also contacting Western governments, they said. “We are seeing members of Bashar Assad's inner circle make plans to leave," a senior US official in Washington told the newspaper. The secret preparations include moving large sums of money offshore into Lebanese and Chinese banks, the Telegraph said. The French foreign ministry, meanwhile, called for the Syrian military to desert en masse the day after the pilot's defection to Jordan. “Yesterday's defection leads us to call on members of the Syrian army and security forces to continue these defections," ministry spokesman Bernard Valero told journalists. Meanwhile, troops shelled rebel strongholds across Syria in Homs, Daraa and Idlib. Security forces rained down shells on several districts of the central city of Homs where at least 31 people were killed the day before in a steady bombardment, activists said.