The Syrian central city of Homs was undergoing heavy shelling on Tuesday, activists said, with security forces seeking to seize a key neighbourhood where rebel forces have a significant presence. \"The neighbourhood of Baba Amr has been undergoing shelling since early morning and there is a bid to launch an assault on the area where heavy gunfire can be overheard,\" the Syrian Observatory for Human Rights said. The Britain-based group said nearly 70 civilians were killed in Homs and its environs on Monday amid the fiercest assault yet on the protest hub since the outbreak of a nationwide popular revolt against the regime of Bashar al-Assad. Nearly 30 were also killed in clashes elsewhere, including Idlib in the northwest and in districts near Damascus, where clashes were continuing on Tuesday. The government has blamed the violence on \"armed terrorist gangs\" and has vowed to pursue its assault on Homs. \"Operations to hunt down terrorist groups will continue until security and order are re-established in all neighbourhoods of Homs and its environs and until we overcome all armed persons terrorising citizens and threatening their life,\" it added. Abu Rami, an activist in Homs reached by telephone, said the shelling of the city had continued through the night. \"There are about four blasts every five minutes,\" he said. \"Since this morning the shelling has been concentrated in the neighbourhoods of Baba Amro, Inshaat and Jubar. \"The humanitarian situation is dire. No one can move around. There are snipers everywhere,\" he added. Hadi al-Abdallah, another activist, said residents overnight had taken advantage of a 30-minute lull in the shelling to recover the bodies of dozens of victims and immediately bury them. \"No one can leave Baba Amr as it is completely surrounded,\" he told AFP. \"There are some buildings hit that we haven\'t been able to reach because of the intensity of the shelling. \"We don\'t know if there are wounded or dead inside.\" He said one field hospital was still operating in the city but was lacking even basic supplies as well as blood. \"The army is trying to choke off the city before launching a final assault,\" he said. Clashes were also reported in other parts of Syria on Tuesday including Hula, located in Homs province, where a 15-year-old boy was reported killed. In Idlib, the army was shelling the village of Kafar Takharim, where there are members of the Free Syrian Army, made up of defectors and sympathisers, activists said. \"There are fierce clashes between soldiers and defectors,\" said the Local Coordination Committees, a loose umbrella organisation of opposition activists. Clashes were also taking place in Basr al-Harir, in the southern province of Daraa, where 70 soldiers had defected, the LCC said. According to rights groups, more than 6,000 people have died since the outbreak of the revolt in Syria mid-March.