Earlier, we reported that Lotus has in China finally taken delivery of the latest incarnation of Renault's turbo V6 'power unit', as used by Red Bull and sister team Toro Rosso in Bahrain.
Italy's Autosprint had said the struggling Enstone team was unable to use the unit two weeks ago due to "other technical difficulties" with the E22 car.
But it appears there is more to the story.
Schmidt claims Renault, having invested only half the money in its V6 programme compared to dominant Mercedes, has been unable to produce enough parts to supply all of its team partners with the latest 2014 unit.
"As the unofficial works team, Red Bull gets the best service," he explained.
And as Red Bull has drafted its second team Toro Rosso into the process of speeding up the fixes to Renault's problems, the Faenza team has "also benefitted by getting the better engines every now and then", Schmidt added.
The Auto Motor und Sport report claimed that, in some cases, the engines used by Lotus this year have been 30 horse power off the pace of the leading Red Bull versions.
"Lotus is now sounding the alarm and is calling on Renault for equality with Red Bull," said Schmidt.
He explained that Red Bull has defended its status on the basis that title sponsor Infiniti is putting money into the engine development, but nonetheless Lotus will get full equality as from next month's Spanish grand prix.
"It is only a matter of time before we can deliver what we expect from the car," Lotus' Alan Permane is quoted as saying.