GENEVA (Reuters) - Rival armed groups may have killed hundreds of civilians in massacres and other “incomprehensibly vicious” attacks in eastern parts of the Democratic Republic of Congo (DRC), senior UN officials said on Wednesday. The violence is focused in North Kivu near the border with Rwanda where warring groups have targeted villages seen as supporting their opponents, while the national army has been diverted to fight a movement of mutineers known as M23. “The deterioration of the overall security situation in North Kivu following the M23 mutiny and related ruthless attacks against civilians is extremely alarming,” said Roger Meece, special representative of Ban Ki-moon.