British FTSE 100 tumbled on Thursday pushed down by Barclays amid concerns EU summit will not provide any consensus on how to tame region's debt crisis. Barclays Plc plunged 16% after the lender was fined USD 452 million for manipulation of interbank rates Euribor and Libor. Other UK financial institutions also posted broad losses. HSBC Holdings dropped 3.4% and Royal Bank of Scotland Group sank 9.9%. Reckitt Benckiser deteriorated 2.5% after Credit Suisse downgraded the consumer-products company from outperform to neutral. Currently FTSE 100 trades 1.1% lower at 5,465.