British Transport police evacuated Waterloo, Waterloo East and Victoria stations just before 5pm after a coded telephone warning from the IRA that two bombs had been planted. Services from Charing Cross were also suspended.
The chaos was compounded by the brief closure of Euston station because of a fire alert.
London Underground trains continued running, but streets around Victoria and Waterloo were closed, adding to rush-hour traffic jams. Waterloo and Charing Cross stations were reopened at about 7.30pm. Victoria was closed for a second time after a suspicious package was found.