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* FTSE 100 flat
* RBS, Barclays under pressure
* Mining firms rally
By Kit Rees
LONDON, Jan 16 (Reuters) - Britain's top share index toucheda fresh record high on Monday in choppy trade after sterlingtumbled to a three-month low on worries that Britain was headedfor a "hard" Brexit from the European Union.
The blue chip FTSE 100 index was flat in percentageterms by 0858 GMT, touching a fresh all-time high of 7,354.14points earlier in the session, outperforming its European peers.
The more domestically-exposed FTSE 250 index fell0.1 percent.
Sterling dropped as much as 1.5 percent following mediareports that Prime Minister Theresa May will signal a "hard"Brexit for Britain from the European Union in her speech onTuesday.
A "hard" Brexit scenario would prioritise immigrationcontrols and bilateral trade deals that would see Britainleaving the EU's single market and customs union.
Banking stocks were the top fallers, with RoyalBank of Scotland and Barclays both down morethan 2 percent.
"Having access to the single market is key for (the banks),or indeed if they can't have access, then what the particularrequirements of the passporting might be for them to be able tostill do business across Europe," Dafydd Davies, partner atCharles Hanover Investments, said.
"If it is a genuinely hard Brexit and then they have to lookat relocation costs, that could be quite substantial for them.However at the moment, it's very much a wait-and-see situation."
A drop in sterling, however, benefits the FTSE 100'sinternational, dollar-earning firms, giving them acurrency-related accounting boost. In 2016, the FTSE 100 was thebest performer among major regional indexes in Europe, gainingmore than 14 percent.
Mining companies were among the biggest risers among theblue chips, with Anglo American, BHP Billiton and Glencore all up between 0.8 percent to 1.9 percent.Precious metals miners Randgold Resources and Fresnillo both rose around 1.2 percent, helped by a firmer goldprice. (Reporting by Kit Rees; Editing by Janet Lawrence)