COLOMBO (Agencies) Two people have been killed in separate attacks ahead of a presidential election next week. A supporter of opposition candidate Gen Sarath Fonseka was killed in a clash involving ruling party activists in the north-western town of Waryiapola. Later, a ruling party supporter was killed in a nearby town when a campaign office was bombed, marking the fourth politically-related death in the run-up to the presidential vote on January 26, taking place amid heightened tension. There have also been 695 incidents of polls related violence Gen Fonseka is the main rival to President Rajapaksa. He resigned from his post as chief of defence staff in November following differences with the government over who should take credit for defeating the Tamil Tigers last May. In the attack in Waryiapola, about 60km north-east of Colombo, supporters of Gen Fonseka were attacked while putting up election posters. One man was killed and several others sustained injuries, a spokesman for the police election secretariat said. Sources said the man was clubbed to death at Ambakadawara, Wariyapola by a gang alleged to be supporters of the ruling United Peoples Freedom Alliance (UPFA). A group of ten supporters of Gen. Fonseka had reportedly been pasting posters, when they came under attack by a gang on motorcycles. The supporters had fled to escape the attack, but one of them was killed. The victim H.M. Dhammika Herath (33) was a businessman in the area and the son of the former Principal of Amakadawara Vidyalaya. The body was to be sent from Wariyapola District Hospital to the Kurunegala Teaching Hospital for a post-mortem. In connection with the killing the police was able to arrest five out of the six suspects who came in six motorbikes. The bomb attack in Kurunegala, about 15km south-east of Waryiapola, came a few hours later. At least six people were injured. IOne person was killed and four injured when a hand grenade was thrown at a residence which was also the election office of Minister Jayaratne Herath. The victim was Suranga Indrajith (28) a driver attached to the Ministry of Health, police media spokesman I.M. Karunaratne said. Meanwhile, in yet another incident of polls related violence, the Opposition Leader of the Dambulla Pradeshiya Sabha was stabbed by a group of four men Monday morning. The victim A.V. Rupasinghe received serious injuries to his chest area, police said. He was admitted to the Dambulla Hospital and was transferred to the Kandy General Hospital due to his critical condition and is now receiving treatment at the Intensive Care Unit (ICU). The masked men had entered the house as he was sleeping at the time of the incident, the Sigiriya police said. According to the owners the mob has entered the house by breaking down the front door with iron bars.The armed men had then threatened the members of the family saying that they would be assaulted if they started shouting, Dambulla police said. President Mahinda Rajapaksa has instructed Central Province DIG Pujitha Jayasundera to conduct an independent investigation into the incident and arrest the suspects. Previous elections in Sri Lanka have been marred by violence. Police say they have received reports of about 600 incidents of violence connected to the forthcoming election. President Rajapaksa, who is running for a second term, has ordered a security crackdown, his spokesman Chandrapala Liyanage said. The president is deeply concerned about the violence and has already ordered police to make sure that there is tighter security, Liyanage has been quoted as saying. He is also appealing to all parties to ensure there is no violence. A supporter of Gen Fonseka - 60-year-old Kusuma Kuruppuarachchi - was the first to be killed in the campaign when she was shot in the southern town of Hungama last week. On Saturday 19-year-old Aruna Saman Kumara, a supporter of the ruling coalition, was killed in a clash with supporters of Gen Fonseka. Police also fired tear gas to disperse thousands of party workers in the eastern town of Polonnaruwa after mobs destroyed vehicles and buildings on Wednesday. Opposition leader Ranil Wickremesinghe has accused Rajapaksas Peoples Alliance of inciting violence and using intimidation to swing voters. Rajapaksa is facing a tough challenge from Fonseka, who quit the army and entered politics in November. The Sri Lankan army defeated the Tamil Tiger rebels last May, ending 26 years of civil war. The rebels were fighting for a separate Tamil homeland.