By Andrew Cawthorne CARACAS (Reuters) - Venezuelan President Nicolas Maduro has called for legal action against a former government official who now teaches at Harvard University and wrote an opinion piece that contributed to a fall in the nation's bond prices earlier this week. Ricardo Hausmann, a Venezuelan planning minister in the 1990s, wrote that Venezuela was in arrears across various sectors of the economy and had "defaulted" on its people. "So, should Venezuela default on its foreign bonds?" he asked. Combined with pessimism on Wall Street over lack of market-friendly reforms, last week's article on Project Syndicate, a web portal that carries opinion pieces on global affairs, hit Venezuelan bond prices.