European Union foreign policy chief Javier Solana on Tuesday said he was "very concerned" about the recent outbreak of violence in Democratic Republic of Congo. Solana spoke via telephone with DR Congo President Joseph Kabila as well as Kabila's main rival in recent polls, Vice President Jean- Pierre Bemba, telling both men that the outbreak of violence was "not acceptable." Three days of fighting between armed militias loyal to both men has brought chaos to the DR Congo capital Kinshasa. Clashes broke out Sunday after results of July polls were announced; with no clear winner, Kabila and former rebel warlord Bemba will face off in a second-round run-off. A statement released by Solana's office said he had underlined that differences must be settled by peaceful means, and that the election campaign for the upcoming run-off polls must be conducted in a responsible manner. Solana also praised the role of EU and UN troops in helping to restore calm in Kinshasa.