Aug 20 (Reuters) - A collapse in Afghanistan’s gross domestic product of 10% to 20% cannot be ruled out following the Taliban’s takeover of the country, the research and risk analysis arm of rating agency Fitch told Reuters. “It is hard to see how the country will achieve any positive growth this year,” Anwita Basu, Head of Asia Country Risk, Fitch Solutions, said on Friday. Reporting by Kanishka Singh in Bengaluru Editing by Gareth Jones Our Standards: The Thomson Reuters Trust Principles.