(Reuters) - China should prepare for potential U.S. sanctions by increasing use of its own financial messaging network for cross-border transactions in the mainland, Hong Kong and Macau, according to a report from the investment banking unit of Bank of China. Chinese state lenders have been revamping contingency plans in anticipation of U.S. legislation that could penalise banks for serving officials who implement the new national security for Hong Kong, Reuters reported earlier this month.