US consular staff in London, ­Mexico City and New Delhi have stepped in to help with a ­crisis in issuing US passports that some members of Congress have compared to the response to Hurricane Katrina.

People with knowledge of the situation said some of the biggest consulates overseas have been assisting in renewing passports for US residents, although not with issuing first-time passports. The London embassy alone is thought to have processed 12,000 passports for US resident citizens. Such work is normally done at centres within the US.