Commuters on the platform at Seven Kings station (Image: Archant)
Disruption is expected on Greater Anglia trains between Liverpool Street and Shenfield until around 10am.
The operator said electrical supply problems between Chadwell Heath and Manor Park caused delays earlier this morning.
Services through Ilford and Romford are returning to normal but running with delays of up to 10 minutes. Stops may be changed at short notice.
Train tickets will be accepted on buses between Ilford and Stratford until 9.30am.
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