Pirelli's Paul Hembery has admitted that determination of all F1 teams to keep information to themselves is hindering development of next year's tyres.

Speaking in the wake of the FIA's decision to bar McLaren from joining forces with the Italian manufacturer at a private test in Austin later this month, Hembery also revealed that he felt that teams were also withholding data that would hasten the finalisation of the 2014-spec rubber.

Although the dimensions of next year's tyres will remain the same as 2013, the structure is still being finalised as Pirelli fears that the new engine and drivetrain package being introduced to F1 in 2014 will require a different construction to cope. However, without complete openness from the teams, Hembery fears that the development process will be hampered.

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"The real impact for us will be in terms of torque, wheelspin and lack of downforce, which is heavily compound-dependent," Hembery was quoted by Sky Sports, "and I don't think anybody really knows [what the true figures are].

"All the suggestions are that it's going to be a very strange start up and a very big difference for drivers, teams and ourselves. We're worried a little bit about the differences in balance, and maybe we need to do something different on the rear tyre due to the torque that I mentioned.

"If you look at data from the teams, there are huge disparities, so we maybe need to do another survey in a month's time to see if there's been any updates to that. We're not going to really get all the correct data because of the paranoia in F1."

Hembery also suspects that protests from rival teams may have prompted the FIA to scupper the planned test with McLaren, despite the outing at the Circuit of the Americas supposedly using a 2011-spec car and test drivers Oliver Turvey and Kevin Magnussen.

"To say it's not ideal is a bit of an understatement, but we understand that maybe there's some objections from a couple of teams," the Briton conceded, confirming that both Pirelli and McLaren had been forced to reveal the intention to test following the furore that surrounded Mercedes 'secret' session in Barcelona in May.

"That's part of the process - that you don't cross any boundaries after the Mercedes test. That's why you have the process of approval. Those are the reasons given and we have to accept them and find another solution."