Services on a key transport route to the Olympic Park were suspended earlier this week after a fire alert.
The problem meant no trains were running on a section of the Tube's Central line which serves the Olympic Park station of Stratford.
The Central line was suspended between Liverpool Street and Woodford/Newbury in both directions.
A Transport for London (TfL) spokesman said: "The suspension is due to a train being taken out of service at Leyton after the driver reported smelling smoke. This has been investigated and all passengers left the train and station without reported problems."
TfL advised Olympic spectators to use other Tube and main line services to reach Stratford, including the Underground's Jubilee line, the London Overground and the Docklands Light Railway.
The problems come on a busy day day for travel in the capital with Team GB competing in events at many venues, and picking up medals in shooting, rowing, canoeing and judo.
Posted 02/08/2012 by email@example.com