Cyril Abiteboul has called the official line regarding Red Bull’s move from Renault to Honda power a "joke".
As Red Bull drops Renault to become the works Honda team from 2019, Red Bull chiefs have consistently criticised Renault whilst saying everything about the Honda future looks rosy.
"I think Daniel (Ricciardo) was not impressed with the Red Bull communication where Honda always seems perfect," Renault boss Abiteboul said at Spa.
"It’s completely unfair to Renault. Honda is in evolution, but when I see what Toro Rosso says and at the same time Honda is already on its 11th, 12th engine, frankly it’s a joke.
"It can influence a driver like Pierre Gasly, but not one like Daniel," he added.
"I don’t think Daniel believes in how perfect Honda is," Abiteboul said.
In contrast, the Frenchman said Renault was very open and honest with Ricciardo in terms of what the Enstone team could offer him for 2019 and beyond.
"We always put the facts on the table," said Abiteboul.
"Daniel knew our offer in terms of financial conditions, but in terms of technical possibilities we know what we have to do.
"We know we are not yet on the level of Red Bull Racing and even in 2019 this will not happen. Daniel knows this," he added.