Russian President Vladimir Putin warned Monday of a protracted civil war in Syria should President Bashar Assad be \"unconstitutionally\" removed from power by rebel fighters. \"We are afraid that if the country\'s current leadership is removed from power unconstitutionally, then the opposition and today\'s leadership may simply change places,\" Russian news agencies quoted Putin as saying. \"One will become (the new) leadership and the other -- the opposition,\" Putin was quoted as saying after talks with visiting Italian Prime Minister Mario Monti. Putin warned that in that case \"a civil war will stretch on for who knows how long\". \"We do not want the situation to develop according to the bloody scenario of civil war and continue for no-one knows how many years as it happened in Afghanistan,\" Putin was quoted as saying in the Black Sea resort of Sochi. He once again called on both sides in the 16-month conflict to sit down for talks that could help end fighting Syrian activists say has claimed more than 17,000 lives. \"The Syrian leadership as well as the opposition should find the strength and organise a negotiating process framing it in such a way that it would be possible to achieve an acceptable compromise on the country\'s future.\" \"Both the government and the opposition should cease violence and sit at the negotiating table and decide there how the country will live in the future. Putin stressed that Syria\'s political future should not be decided on the battleground. \"I believe that the future of the country should be decided not on the basis of a military victory or defeat of one of the sides but on the basis of negotiations and compromise,\" Putin was quoted as saying. The Russian leader\'s comments came as fighting raged in the main Syrian cities of Damascus and Aleppo on Monday.