LONDON (Reuters) – The world’s top association of ship certifiers has withdrawn membership from the Russia Maritime Register of Shipping (RS) due to the impact of sanctions on Moscow after its invasion of Ukraine, in another blow to the country’s vital shipping sector. Classification societies provide services such as checking that ships are seaworthy, and this certification cover is essential for securing insurance and entry into ports. In recent days, Britain’s LR and Denmark’s DNV, have both announced they were stopping or winding down their business ties with Russia. The International Asso…