* Martin Scicluna to become chairman on Jan. 1
* Steps down as non-exec at Lloyds
* Shares up 0.7 percent
LONDON, Nov 22 (Reuters) - RSA, Britain's biggest commercial insurer, appointed Martin Scicluna, a 30-year veteran of accountancy firm Deloitte, as its new chairman.
Scicluna, who chaired Deloitte from 1995 to 2007, will take up his new role on January 1, replacing John Napier, who is stepping down after 10 years, RSA said in a statement on Thursday.
British corporate governance rules require companies to replace their chairmen every nine years to ensure they remain independent from executive directors and can continue to defend shareholders' interests.
RSA, best known in Britain for its More Than home and motor insurance business, is trying to expand in Latin America and other emerging markets to offset sluggish growth in its established European markets.
Some analysts believe weak revenue growth could crimp RSA's profits and undermine its ability to grow its dividend, among the biggest relative to share price of any large British listed firm.
Scicluna will quit his current role as non-executive director and chairman of the audit committee at Lloyds Banking Group in March next year, Lloyds said.
Scicluna is also chairman of property firm Great Portland Estates.
RSA shares were up 0.7 percent by 0815 GMT, in line with the FTSE 100 share index. The stock is up 5.7 percent since the start of the year, lagging an 18 percent rise in the FTSE non-life insurance index.