MOSCOW -- The Russian army said on Saturday more than 13,000 rebels had been killed in Chechnya since the start of a military operation against separatist groups in the republic in October 1999. In the last week 20 rebels had been killed by Russian forces, AFP quoted staff officers saying based at the army's Chechen headquarters in Khankala, near the Chechen capital Grozny. They said that one Russian soldier had been killed by a landmine during the same period. The figures are impossible to confirm independently. Russian officials last published official figures at the start of 2002, when they said that 3,500 rebels had been killed since October 1999. At the time non-governmental organizations estimated that rebel losses were at least double the figure.