Business leaders want London's congestion charge to be changed or temporarily axed to support the hospitality industry following the terrorist bombings in July.
The Forum of Private Businesses (FPB) wants to see the charge, which runs from 7am to 6.30pm Monday to Friday, suspended for six months.
A combination of a hike in charges, which rose by 60% to 8 in July, terrorism fears, tube disruption and the holiday season saw retail sales in July tumble by 8.9% year-on-year.
This is the worst fall recorded in central London since the London Retail Consortium started collecting data in October 2002. Research company SPSL found shopper numbers were down by 12.6% during July across all retail outlets in central London, including restaurants.
Bob Cotton, chief executive of the British Hospitality Association, said the charge hours should be adjusted over the next three months.
It should end earlier than 6.30pm, as a lot of restaurants are missing out on the pre-theatre dinner market."
Ashley Sumner, owner of the Grocer restaurant and delis in central London, said: "There was a definite drop in numbers after the bombings and each consecutive Thursday has been unbelievably ghostly.
"Restaurants used to trade from 5.30pm, but now we're lucky to get anyone by 7.30pm so we're being forced into being a one-sitting restaurant."
A spokesman for Transport for London (TfL) said discussions were under way to change the cut-off time from 6.30pm to 6pm.