Greece will decide next week when the Athens stock exchange will reopen, after a four week-long shutdown made necessary when capital controls were imposed last month, a government official said on Thursday. The stock exchange has been closed since June 29 when Greece shut its banks and imposed capital controls to ward of a collapse of its banking system after the country rejected a cash-for-reforms deal in a referendum. The official confirmed that talks with Greece's international creditors on a third bailout would start in Athens on Friday and that the government wants the talks to be concluded by Aug 20.