The London Fire Brigade has attended reports of the smell of smoke coming from a Jubilee Line tunnel between London Bridge and Southwark.
The incident saw the Jubilee line being temporarily suspended between Canary Wharf and London Waterloo just after 3pm as firefighters carried out an investigation.
A spokesperson for the London Fire Brigade said that they had conducted a search of the tunnel and had found no fire.
Although service was restored to the Jubilee Line just before 4pm, severe delays are expected throughout the line in the run up to rush hour, causing fears for travel chaos.
Responding to a question on Twitter, a Transport for London spokesperson explained: "After a suspension the service needs to regulate back to timetable. The delays are a result of the suspension."
It remains unclear how long the line will remain with severe delays, despite no fire being found in the tunnels. Tickets are being accepted on London busses, South Eastern Trains and the DLR.
A number of Londoners have taken to Twitter to warn others to avoid the line.