ZURICH, March 20 (Reuters) - Credit Suisse and UBS could benefit from more than 260 billion Swiss francs ($280 billion) in state and central bank support, a third of the country's gross domestic product, as part of their merger to buffer Switzerland against global financial turmoil, documents outlining the deal show. "The government's going to have to say to voters why they are putting citizens' money, taxpayer money at risk to bail out a bank that was predominantly servicing the ultra wealthy, doing some pretty extraordinary things with its investment bank and paying people crazy amounts of money relative to what the man in the street gets paid," one former global bank CEO, who did not wish to be identified, told Reuters. "The bankruptcy of Credit Suisse would have had a huge collateral damage - on the Swiss financial market also, risk of contagion for UBS and other banks, and also internationally," Swiss Finance Minister Karin Keller-Sutter told a press conference