"Moscow's richest 10 percent earned 41 times more in 2006 than the poorest 10 percent," state statistics service assistant director Leonid Arshon told AFP.

Nationwide, there was a 15-fold gap in earnings, he said -- up from a gap of 10 times in 2001 and 14 times in 2003.

Russian Academy of Sciences economist Ruslan Grinberg warned that in countries where the gap is a factor of 10 or higher, "the conditions are created for social disorder."

"The only place that rule doesn't hold is in America, where the coefficient holds steady at 10-12. But there it is considered normal, since their philosophy differs from ours," he told daily newspaper Izvestia.