Kazakhmys, the UK-listed Kazakh copper producer, and Metalloinvest, the Russian iron ore and steel group, have held early-stage talks about combining to form a metals group that could be worth more than $40bn.

Analysts said there was considerable industrial logic for the consolidation of assets across the former Soviet Union into larger companies resembling western diversified mining houses such as Rio Tinto and BHP Billiton, but there would be political obstacles.