Red Bull has launched an official protest against Mercedes in the wake of their rivals conducting a secret tyre test with Pirelli.
The move comes ahead of the Monaco Grand Prix, with Red Bull team principal Christian Horner citing a lack of transparency.
"We feel it's not in line with the rules so that's why we've protested before the race. We just want clarity," said Horner.
Under the sporting regulations in-season testing is banned, however, it is understood in Pirelli's tyre-supply contract they are allowed private tests with individual teams should circumstances require.
With Pirelli due to slightly alter the structure of their rubber on safety grounds from next month's Canadian Grand Prix, and with tyres for 2014 due to change considerably given the new engine regulations, the Italian manufacturer felt it crucial the tyres were tested.
Despite that, it is the manner in which the test has taken place that angers Horner, who only discovered the situation last night.
He added: "There is confusion between what is contractually permissible and what a team is allowed to do in the sporting regs.
"It's a situation we need clarification on, and our position is we are going to request that clarification.
"I can understand Pirelli wanting to test the tyres, they've obviously got issues with the tyres.
"What's disappointing is it's been done in a manner that is not transparent, that a three-day test has taken place with a current car running on tyres that are going to be used at the next grand prix.
"Irrespective of what you call it, that's testing."
As to whether Horner receives the clarity he seeks is another matter as he said: "It's important it's brought to a head, and I don't think we're the only team that feels that way.
"I don't think it's Pirelli's fault. They need to resolve their situation out.
"The problem is the manner in which this has been dealt with has not been right."
Niki Lauda, the non-executive chairman of Mercedes GP, has confirmed the team were given permission by the FIA to conduct the test after seeking clarification.
Speaking to SkySportsF1, three-times F1 world champion Lauda said: "It is very simple, we asked the FIA 'Are we allowed to do this?'
"The FIA confirmed it and said 'yes', so therefore we did the test. I think other teams have been asked too.
"There was one team that tested earlier. These tests can always come in cases of emergency, so Mercedes did absolutely nothing wrong.
"We asked the right people for permission and we got it."
Pirelli motorsport director Paul Hembery also claims the test was above board and does not believe Mercedes has gained any advantage.
"It's completely regular in that we are allowed to do a 1000-kilometre tyre test with any team," said Hembery.
"In the World Rally Championship contract it's exactly the same. We can do it with a representative car.
"We've done it before with another team, and we've asked another team to do some work as well.
"In reality, we were looking at next year's solutions and trying a variety of different things.
"Mercedes haven't a clue what on earth we were testing in reality."
Asked about the prospect of Mercedes gaining the upper hand, Hembery added: "Absolutely not, no, because it's of no relevance to what's happening here.
"The bottom line is we've been trying to find a way to test."
Regarding whether it was with this year's tyres or those for next year, Hembery said: "Ninety per cent next year. We changed at the last minute."