Businesses and homes in central London faced the threat of further power cuts Friday, electricity company EDF Energy said, warning customers to turn off air-conditioning to ease demand.
The city's main shopping areas of Oxford Street, Regent Street and Soho — all hugely popular with tourists — were hit by cuts on Thursday, when traders were forced to close after tills, lights and air-conditioning stopped working.
High demand for electricity because of Britain's ongoing heatwave helped trigger four unrelated outages over the past few days, EDF Energy said.
The firm, the British arm of French power group EDF, said it had worked on repairs through the night and its engineers were making "good progress".
But in a statement it added: "There is still a significant risk that power interruptions may occur in the Soho area today."
The same areas that were hit on Thursday could be affected again, it said.
Oxford Circus Underground station, one of the busiest on the London network, was closed for an hour-and-a-half the previous day and clothing retailer Topshop shut its flagship store three hours early as a result of the outages.
Jace Tyrrell, spokesman for the New West End Company which represents businesses in the area, said: "This is bad news for business and bad news for shoppers in the West End."
Temperatures in central London were forecast to hit 30 degrees Celsius (86 Fahrenheit) with 83 percent humidity on Friday.
Just over a week ago southern Britain recorded an all-time high for July of 36.5 degrees Celsius (97.7 Fahrenheit).
