McLaren boss Zak Brown says he has no interest in fulfilling Red Bull's hefty financial demands linked to an early release of Toro Rosso technical director James Key.
McLaren has hired the British engineer to move to Woking sometime in the future, but in the interim Key remains contracted to Toro Rosso, and any premature departure would entail a healthy compensation fee according to Red Bull motorsport boss Helmut Marko.
"We told McLaren what would solve the problem, and we didn't hear anything," Marko told Motorsport.com.
"We are not in a hurry. It's financial – we don't mix things."
Preliminary discussions between the two parties have now ground to a halt, with McLaren unwilling to comply with its rival's demands.
"We're in no dialogue with them," Brown told Motorsport.com.
"They have named their terms. I'm not interested in the terms that they've put forward."
"We have signed a contract with James, so he will be joining McLaren as technical director. We're still working through the timing of that.
"I think it's high unlikely that he will join us this season – and we don't have a specific start date yet."
An interesting footnote that has emerged from the negotiations is the potential fate that could befall McLaren junior Lando Norris at the end of this month.
The 18-year-old is a contender for a seat at McLaren, Brown confirmed in Monza. However, the team's option on Norris expires on September 30, leaving him a free agent after that date.
Recent reports suggested that McLaren would be prepared to offer Norris to Toro Rosso as part of a compensation awarded to Red Bull for Key's early release.
But Marko rightly noted that such an eventuality would not be necessary given the driver's almost expired contract with McLaren.
"At the moment there's a clear situation," said Marko. 'If they give him a drive by the end of September, he is fixed. If not he is free."