Police in Sierra Leone said Friday they had imposed a curfew in Kailahun in the east after violence intensified in a run-off to presidential election scheduled for September 8, DPA reported. Police Assistant Inspector General, Chris Charlie, who is in charge of professional standards and the media, said a probe into renewed violence has begun. Violence has overshadowed preparations for next Saturday's presidential run-off elections between Vice President Solomon Berewa and opposition candidate Ernest Koroma. Koroma's APC won 44 per cent of the polls over 38 per cent for the ruling SLPP candidate Berewa thus setting the stage for a run-off. Since the campaign was declared open last week, reports say rival supporters of both political parties have engaged in violent clashes. Unidentified men allegedly torched houses in Segbema where the violence has escalated. The APC's Ernest Koroma has intensified his campaigning in the eastern and southern provinces this week, a stronghold of the ruling SLPP. "Indeed there were some skirmishes between rival parties in on 30th of August 2007," Assistant Police Inspector General Charlie said but denied that the SLPP party building had been burnt to the ground. Inspector Charlie said police have been working around the clock to protect all candidates during the election. "Our presence is all over the provinces, especially in that part of the country," he said, adding, that the APC candidate and partisans had been provided with the "best security." Police have not confirmed which group is responsible for the alleged violence. "We can only determine that one when there is a full-scale investigation, which the regional commissioner in the south and eastern provinces has now mounted," Charlie said. Political observers say the violence is likely to mar gains made during the second post-war election solely supervised by Sierra Leoneans themselves. Meanwhile, reports from the Liberian border town of Bo Waterside say hundreds of Sierra Leoneans have trekked there to escape potential violence ahead of run-off presidential election. The local immigration commander at Bo Waterside, in Grand Cape Mount County, said several of them have been denied entry into Liberia. Lt. Col. Ada Obiemiwe said many have no travel documents to enter the country. Sources at the border said most were nationals of Sierra Leone, Nigeria and Guinea. "I cannot talk to the press now because I am on my way to conduct regular immigration patrol at the various border points," Ada said.