The City of London is Europe's main financial centre but it must be built on solid foundations in a single market, the EU's internal market chief said Thursday.Speaking on the BBC Radio Michel Barnier said he was working to implement the G20 plans to tackle the economic crisis.This meant a "single market for financial services within these 27 countries".Asked whether, whatever happens to the euro, would the single market survive, Barnier said "The financial crisis which came from the US and the crisis of sovereign debt which has Europe as its epicentre has wider economic consequences."We can see growth has slowed and there are too many unemployed people."But the single market has the capacity to grow and it is affected by this financial crisis. Now there is an additional reason for us to meet because there is a problem for the 27 countries in this big market.It can work better from the point of view of mobility, exports, innovation and national risk."I want to build a single market for financial services within these 27 countries." Michel was asked if this meant more regulations for the City of London (the financial and banking district here) and if he saw it as a "battle" between Brussels and Britain.Michel, speaking in his native French which was translated, replied "I want the City of London, which is the main European financial market place, to be upheld and supported. It will be if it has safer and healthier foundations, such as those which the G20 has asked for.What I'm doing is clearly implementing the G20 agenda which Britain has signed. I think there is financial incentives and interest in having safer and more secure foundations and it would be more competitive."So that is what I'm giving my attention to. I think the regulations I've proposed are laid down by the G20. I want to bring the UK on board."I'm very clear and determined about this: there must be a single Europe with 27 countries. Some of them have chosen to move a bit faster by having a single currency.But there is a single European political and economic area and I very much hold to the unity of 27 countries in the single market. I believe the single currency is a matter for all the European countries, even though some have chosen to opt out. But those who want to come in can do so" he said.