KABUL, Aug 18 (Reuters) - About 5,000 diplomats, security staff, aid workers and Afghans have been evacuated from the capital Kabul in the last 24 hours, a Western official told Reuters on Wednesday. The evacuations by military flights will continue around the clock, he said, adding that clearing the chaos outside the airport was a challenge. Reporting by Rupam Nair; Writing by Nick Macfie; Editing by Andrew Cawthorne Our Standards: The Thomson Reuters Trust Principles.