* Santander, Halifax gain most customers
* Barclays has biggest net loss of customers
LONDON, July 22 (Reuters) - New rules making it easier forBritons to switch banks resulted in a 4 percent increase incustomers moving accounts in the year to the end of June, thebody overseeing the system said on Wednesday.
Data from Bacs showed that there were 1.1 million switchescompared with 1.06 million over the same period one year before.
The new rules, introduced in October 2013, ensure customerscan switch accounts within seven working days, with all outgoingand incoming payments automatically transferred. Bacs said 69percent of Britons were now aware of the service compared with58 percent in the month of its launch.
The rules are part of measures designed to break thedominance of Britain's five biggest banks - Lloyds, RBS, Barclays, HSBC and Santander UK - which provide more than four out of five UK personalcurrent accounts.
Britain's competition watchdog is investigating whetherthere is effective competition in the market for personalcurrent accounts and is due to report its findings by the end ofSeptember.
The Competition and Markets Authority (CMA) said in Novemberthat banks had not done enough to meet the needs of retailcustomers or small businesses. It could recommend banks arebroken up to increase competition.
Santander attracted the most new net accounts,followed by Halifax, which is owned by Lloyds while Barclays and NatWest, owned by RBS, lost the most customers.
Santander has benefited from the popularity of its 1-2-3current account, which pays higher-than-average interest rateson deposits of up to 20,000 pounds. Halifax has offered cashpayments to new customers. (Reporting by Matt Scuffham; Editing by Elaine Hardcastle)