LONDON (AFX) - Britain could join the euro at an exchange rate less than 10 pct below its current level without damaging the economy, according to independent City and academic economists surveyed by the Financial Times. A survey of 20 economists by the newspaper found that the average sustainable entry rate they proposed was 0.68 to the euro. That is roughly equivalent to 2.90 dm to the pound: just 8.5 pct below last night's closing rate, the newspaper said. The expectation that the pound would have to be devalued sharply if Britain were to join the euro has been seen as a significant obstacle to entry, it noted. "Over the past five years the exchange rate has been more stable than at any time since it was floated in the early 1970s," Robert Barrie of Credit Suisse First Boston was quoted as saying. "I don't see why it shouldn't be sustainable." Since 1992, when a sterling value of 2.95 dm proved impossible to defend as the central rate in the exchange rate mechanism, the economy seems to have grown stronger relative to many other European countries, the report said. It is said the French government would be happy for the pound to join at a rate just below 0.68 stg to the euro, which would make France's gross domestic product slightly bigger than Britain's, it added.