UPDATE 1-Britain's big four supermarkets suffer sales falls

(Adds table, details, comment) LONDON, May 6 (Reuters) - Britain's top four supermarkets suffered sales declines in the last three months, industry data showed on Wednesday, as a price war and record grocery deflation continues to hit the sector. After recent signs of a recovery gaining momentum, Britain's biggest supermarket Tesco saw sales fall back 1.0 percent in the 12 weeks to April 26, market researcher Kantar Worldpanel said. The rest of Britain's 'big four' - Asda, Sainsbu