Two other men received sentences of 20 years and 13 years and another two were jailed for two years each.

Energy wealth has enriched Russia over the past decade and attracted thousands of migrants from the former Soviet Union who mostly work in city markets, on building sites, sweeping roads and painting fences. 

Resentment against immigrants has grown in some of the more marginalised segments of Russian society and human rights groups have said that attacks on migrants in Russia are increasing.