By Lawrence White and Iain Withers LONDON (Reuters) – Barclays said on Monday it had identified a single “material weakness” in its internal control processes, as it refiled its accounts with U.S. regulators after a blunder led it to issue more structured notes than it was allowed. The bank disclosed earlier this year that it had to refile an accounting statement known as a form 20-F with the Securities and Exchange Commission because it had sold more structured notes than permitted in the United States. Barclays’ statement on Monday appeared to confirm media reports that the problem related t…