Around 60 people were killed in Syria's Damascus and Homs onTuesday, as an international watchdog said it would probe alleged chlorine attacksin the country.Meanwhile, the parliament speaker said four new candidates had registered for nextmonth's presidential election, expected to return Bashar al-Assad to office despitethe civil war, which has left vast swathes of the country out of his control.A barrage of mortar shells fired by rebels hit a central neighbourhood in the capitalearly Tuesday, killing at least 14 people, state media reported. "Fourteen citizens were killed and 86 others wounded by terrorists who targeted theShaghur neighbourhood in Damascus," the SANA news agency said, using the regimeterm for rebels.The attack hit a school of Islamic jurisprudence where some students are as youngas 14, though it was unclear if children were among the dead. The Syrian Observatory for Human Rights, a Britain-based monitoring group, put thetoll at 17, adding that the figure could rise because several of the injured were incritical condition.Hours later, a car bomb ripped through a crowded area of the country's third cityHoms, followed shortly afterwards by a rocket attack on the same neighbourhood, the provincial governor told AFP.Talal Barazi said 45 people were killed in the double attack on the Zahraneighbourhood."The rocket fell about half an hour after the bombing on the same area, where there was a crowd of people" trying to help those wounded in the blast, he said.The attack was one of the deadliest to hit the central city, where rebels control just afew remaining districts, most of them under a tight government siege. Earlier this month, regime forces launched an attack on rebel areas in the city,where just a few hundred opposition fighters remain after most civilians wereevacuated in a UN-led operation.- Chlorine attacks probe planned -In the Hague, the Organisation for the Prohibition of Chemical Weapons (OPCW) saidit would examine allegations that chlorine had been used in attacks in Syria.The regime and rebels have blamed each other for using chlorine in at least oneattack, in the rebel-held town of Kafr Zita in Hama province, with the oppositionalleging the government has carried out several more.Britain's Daily Telegraph said a team of unnamed experts had found "sizable andunambiguous traces of chlorine and ammonia" in soil samples taken from the sitesof three regime helicopter attacks.It said the findings proved the government was still using chemical agents againstcivilians.The OPCW is already in Syria overseeing a deal under which Damascus is to turnover its chemical weapons arsenal by June 30. On Sunday, the joint UN-OPCW mission in Damascus said 92.5 percent of thecountry's chemical weapons material had been removed or destroyed.Syria agreed to dismantle its chemical weapons programme last year, after Washington threatened military action in response to a sarin gas attack outsideDamascus that killed up to 1,400 people.The regime denied carrying out the attack.- New presidential candidates -In Damascus, parliamentary speaker Mohamed al-Lahham said four more candidateshad registered for the June 3 presidential election, bringing the total number,including Assad, to 11.Ali Wanous, Azza al-Hallaq, Talea Salah Nasser and Samih Mikhael Moussa are allrelative unknowns.Syria's constitution requires that candidates be Muslim, but a source in theconstitutional court confirmed that Moussa is Christian."In the five days after the candidacy period ends, on May 5, we will examine thecandidates to see if they meet all requirements. On May 6, we will announce who has met the conditions," the source said.Hallaq's application brings the number of women competing in the vote to two.The constitution contains no explicit prohibition on female candidates, but itsphrasing implies only male candidates are permitted.The elections will be Syria's first multi-candidate presidential vote after aconstitutional amendment did away with the previous referendum system.But with a brutal civil war raging and large areas of the country held by rebels, itremains unclear how the vote will be organised.Nearly half of Syria's residents have fled their homes, and the electoral commissionsays those who left the country "illegally" will not be allowed to vote. Electoral rules also prevent anyone who has lived outside Syria in the past decadefrom running, effectively excluding most prominent opposition figures, who live inexile.