BEIRUT (Reuters) - Syrian troops drove insurgents from a central district of Homs on Monday, tightening their siege on remaining rebel bastions in the city, which links Damascus to the Mediterranean heartland of President Bashar al-Assad's Alawite sect. The military's gains in Khalidiya district follow a counter-offensive by Assad's forces, which have pushed back rebels around the Syrian capital and retaken several towns and villages near the border with Lebanon in the last few weeks. "As of this morning the armed forces, in collaboration with the National Defense Force, took full control of Khalidiya," an army officer said, referring to the NDF militia which has fought in the offensive, along with Lebanese Hezbollah guerrillas. The officer was speaking to Syrian television in a live broadcast from Khalidiya. Shattered, deserted ruins and weeds sprouting a meter (yard) high in the rubble-filled streets around him showed the scale of the destruction and neglect in a city which was once an industrial powerhouse in Syria. Also badly damaged in the Khalidiya fighting was the distinctive black and white stone mosque housing the shrine of early Islamic military leader Khalid ibn al-Walid. Some activists disputed the capture of Khalidiya district, saying heavy clashes continued on Monday morning, but conceded that army had control of almost the entire neighborhood. The army's progress in Khalidiya comes a month after it launched an offensive in Homs city, building on its capture of the border towns of Qusair and Tel Kalakh, which were both used to bring rebel arms and fighters into Syria from Lebanon. At least 100,000 people have been killed in the Syrian conflict, which started with peaceful protests against Assad's rule in March 2011 but gradually descended into civil war after a military crackdown on the demonstrations. Nearly two million refugees have fled the sectarian-tinged struggle between mainly Sunni Muslim rebels and Assad's Alawite supporters, whose minority sect is a branch of Shi'ite Islam. Regional Sunni powers Saudi Arabia, Qatar and Turkey have backed the rebels, while Shi'ite Iran and Hezbollah have given military support to the Syrian authorities. At the United Nations in New York, Paulo Pinheiro, who chairs a U.N. commission of inquiry on rights abuses in Syria, said countries which armed either side in the conflict were simply helping prolong the suffering. Civilians "come under such sustained and unlawful attacks" that the international community should be shocked into action, Pinheiro told the U.N. General Assembly. "Those who supply arms to the various warring parties are not creating the ground for victory but rather the illusion for victory," Pinheiro said. This is a dangerous and irresponsible illusion as it allows the war to unfurl endlessly before us. Assad has sent reinforcements to the northern city of Aleppo, much of which has been in rebel hands for a year. A coalition of Islamist rebels announced a campaign dubbed "Amputation of the Infidels" against Assad's forces in Aleppo's western districts of Lairamun, Dahr Abed Rebbo and Zahraa. The Syrian Observatory for Human Rights said an overnight attack by the Islamists had killed eight members of the armed forces. Another five defected, according to the British-based monitoring group which has a network of sources in Syria. In the town of Tal Hasel, southeast of Aleppo, Kurdish fighters clashed with Islamists from the al Qaeda-linked Nusra Front, the Observatory said. A Kurdish commander was killed, as well as three Nusra fighters. Kurdish and Nusra fighters have also been battling further east, near the Ras al-Ain border crossing with Turkey. Additional reporting by Michele Nichols at the United Nations; Editing by Alistair Lyon and Angus MacSwan