Dr Helmut Marko has slammed Toto Wolff's position on flexible rear wings in 2021 as "a bit strange".
After the FIA said it would change the flexibility tests from Paul Ricard, Wolff warned that Mercedes could launch a protest this weekend at Baku.
"We find it all a bit strange," Red Bull's F1 supremo Marko told the German-language formel1.de.
"The rules are very clear. The FIA has decided that the tests, especially the one for torsional resistance, will be changed and this will apply from Paul Ricard.
"Wolff believes that the change comes too late, but to my knowledge it is the FIA who determines the procedures in Formula 1," Marko added.
In the event that Wolff does protest, Marko is threatening to fire a counter-protest over the reigning world champion team's supposedly flexible front wings.
"Wolff is of course free to protest, but I believe they will then have to look at their own front wing as well. Images on Servus TV and Sky have shown how drastically their front wing bends down," said Marko.
