Aleppo - Syrian warplanes, artillery and mortar rounds pounded areas in eastern Aleppo on Saturday drawing rebel rockets as government troops gain new ground in the shrinking opposition-held enclave.After four years of holding nearly half of the divided city, rebel fighters have been increasingly squeezed into the centre of the eastern enclave. Government and allied troops, including Lebanese, Iraqi and Iranian fighters, have concentrated their fight on the northeastern part of the enclave, swiftly taking new districts since their offensive began last week. Another front on the southern outskirts of the city has been slower, as rebel fighters push back government advances there.The advances have caused massive displacement. The UN estimated that more than 31 000 have already fled their homes, either to government or Kurdish areas, or deeper into the besieged enclave. The fighting has also intensified the rebel shelling of government-held areas in Aleppo.Machine gun fireThe state broadcaster al-Ikhbariya said "precise operations" by government and allied troops aim to rout out "terrorists," which is how the government refers to all armed opposition groups.The sound of war prevailed in the city early on Saturday. Warplanes made several runs overhead, drawing what appeared to be rebel machine gun fire toward the aircraft.The Syrian Civil Defence in eastern Aleppo said six people were killed in bombings of the central al-Shaar neighbourhood. Opposition news agency Thiqa also put the death toll at six. The Britain-based Syrian Observatory for Human Rights put the death toll at three, adding it was likely to rise. In government-held Aleppo, rebel shelling killed five people, according to the state news agency SANA.To the south of the city, government cannons could be heard firing toward rebel-held areas.Residents in eastern Aleppo also reported intense shelling in al-Sukkari neighbourhood on the southern edge of the enclave, where many of the newly displaced have sought refuge.