MOSCOW, December 14 (RIA Novosti) - The murder rate in Russia in January-November 2006 was 10% less than in the same period of 2005, but 15% of the killings have yet to be solved, an Interior Ministry official said Thursday.

Addressing a news conference, Andrei Kucheryavy, the head of a criminal police department, said: "The number of killings has been gradually declining in the past four years, while the number of solved murders is increasing."

Nearly 23,500 murders have been registered this year, of which 3,500 have not been solved, 9% less than last year. Fifty contract killing cases were sent to court.

Kucheryavy said work to solve serial murders, of which there have been 139 this year, was also a source of concern.

"Analysis of the Interior Ministry's work in the past five years has shown an upward trend in the number of serial killings," Kucheryavy said.