HORSHAM, England — Finance officials from rich and developing countries pledged to boost the role of the International Monetary Fund and make a "sustained effort" to restore global growth after a key conference that sought to bridge deep divisions on how to tackle the financial crisis. The key priority must be restoring frozen bank lending through cash infusions and dealing with the shaky assets souring bank's balance sheets, the gathered finance ministers and central bankers from the Group of 20 countries said in a statement at the end of talks in southern England. The statement did not back a U.S.