By Peter Hobson LONDON (Reuters) – The London Bullion Market Association (LBMA) said on Monday it had suspended its accreditation of six Russian precious metals refiners, meaning they will no longer be able to sell gold and silver in the London market, the world’s largest. The LBMA did not give a reason for the suspension, but the association last week told Reuters it had asked the refiners if they have commercial links with sanctioned Russian entities. Governments including those of the United States and the European Union have imposed sanctions on numerous Russian individuals, companies, ban…