Delivery drivers in the capital currently have unlimited unloading time before 11am, but only 20 minutes after that, making them prone to parking fines.
However, the Freight Transport Association said some London boroughs had indicated they were canvassing views on extending this limit. The FTA is to press for the time to be extended to an hour.
"Fines get bundled into delivery costs, so it's in everyone's interest to resolve this," said Gordon Telling, FTA head of policy for London, south east and east England. The FTA expected a new time limit to be proposed by London councils in early January and hoped it would be adopted quickly, he added.
Spar wholesaler AF Blakemore & Son delivers to 35 outlets in London. "I'd go along with increasing the time for unloading," said Elwyn Davies, its retail development director.
"We find great difficulty in turning our food wagons around in the time available."
John Murphy, director general of the Federation of Wholesale Distributors, said: "This is to be hugely welcomed by an embattled delivery fleet."