The United Nations expressed concern for hundreds of thousands of civilians who have fled Syria's largest city Aleppo amid intensifying clashes between the regime's forces and Syrian Free Army. An estimated 200,000 of the city's 2 million had fled, the UN's Emergency Relief Coordinator Valerie Amos said late Sunday in New York, citing figures from the Red Cross and Red Crescent Societies. "I am extremely concerned by the impact of shelling and use of tanks and other heavy weapons on people in Aleppo," she said. "I call on all parties to the fighting to ensure that they do not target civilians and that they allow humanitarian organizations safe access to bring urgent and life-saving help to people caught up in the fighting." Regime troops intensified their attacks to regain control of areas of the city held by rebels seeking to topple the regime of President Bashar Al-Assad. Helicopter gunships fired on the south-eastern district of Salaheddin, according to the opposition Syrian Observatory for Human Rights. The fighters said they had blocked the army from entering several districts in Aleppo and destroyed tanks. At least 95 people were killed Sunday in Syria, mainly in Aleppo and in suburban areas of Damascus and Daraa in the south, said the opposition. The opposition National Syrian Council planned talks in Cairo on Tuesday to discuss forming a transitional government, member Khaled Khuga told DPA. The weekend's clashes were the heaviest of the uprising which has claimed more than 20,000 lives since it began in March 2011, according to the Syrian Observatory for Human Rights.