TAIPEI, Aug 19 (Reuters) - Taiwan’s finance ministry has called state-owned banks to suggest they buy an “appropriate” amount of stocks amid falls on the island’s stock market, five sources familiar with the matter told Reuters on Thursday. The benchmark index fell more than 2.5% on Thursday, tracking broad falls across other global markets. (Reporting by Liang-sa Loh; Writing by Ben Blanchard; Editing by Himani Sarkar)