Six planes chartered to evacuate hundreds of people from Afghanistan have been unable to leave for days, a top Republican has said

An Afghan official at the airport in the northern city of Mazar-e-Sharif said the passengers were Afghans who did not have passports or visas

But Rep. Michael McCaul of Texas, the top Republican on the U.S. House Foreign Affairs Committee, said that the group included Americans

He said the passengers were on the planed but the Taliban were not letting them take off, effectively 'holding them hostage'