THE number of foreign firms listed on London’s top shares index is set to increase after two Russian mining companies and an Irish construction group were promoted to the higher tier.

Minerals groups Polymetal and Evraz are to enter the FTSE 100 Index in the quarterly reshuffle, along with Dublin’s CRH, while banking group Investec, satellite firm Inmarsat and platinum miner Lonmin will be relegated next Friday.

More than 30% of the FTSE 100 Index is made up of resources companies, many of which are based outside the UK.

The inclusion of big foreign firms has boomed since 2001.

Eric Walker, director of the UK Shareholders’ Association, said: “The index no longer broadly reflects British business interests”.