More than 2,000 civilians have fled across the Congo river to escape fighting between supporters of Democratic Republic of Congo's rival presidential candidates, the U.N. said on Monday, according to Reuters. The clashes at Bolobo, 280 km (175 miles) upriver from the capital Kinshasa, occurred days after electoral authorities last week announced a provisional result giving victory in the Oct. 29 presidential run-off to incumbent President Joseph Kabila. His rival, former rebel chief Jean-Pierre Bemba, has rejected Kabila's victory and filed a complaint with the Supreme Court, which must certify the election result. "I can confirm that some people have fled into the Republic of Congo. We estimate that there are between 2,000 and 2,500," said Jens Hesemann, spokesman for the United Nations High Commission for Refugees in Kinshasa. "They fled due to fighting ... From what we gather it was between supporters of the different presidential candidates." Kabila's and Bemba's supporters and soldiers had fought gun battles in Kinshasa in August and earlier this month. But the clashes in western Bandundu Province, near Equateur province, were the first election-related violence to be reported since Kabila's victory was announced on Wednesday. The result still has to be confirmed by the Supreme Court. Although details were sketchy, authorities in neighbouring Republic of Congo reported that some 1,900 people had crossed the river and taken refuge in the towns of Npouya and Bouemba. "It seems these are followers of President Joseph Kabila, who are in the minority there, who are being beaten up by supporters of Jean-Pierre Bemba," said Clotaire Essieke, the director of humanitarian assistance at Republic of Congo's social affairs ministry. Support for Bemba was strong in western Democratic Republic of Congo, including Kinshasa as well as Bandundu and Equateur provinces. The elections in Congo were the first free polls in the vast, former Belgian colony in more than 40 years. They crowned a peace process that ended a 1998-2003 war, which triggered a humanitarian crisis that has killed over 4 million people through violence, hunger and disease.