BMW has admitted that its concerns about the performance of the Williams team in Formula One this year is delaying the extension of their partnership.
BMW's engine supply contract with Williams runs out at the end of 2004 and talks between the two have gone long past their initial deadline of the beginning of this year.
BMW motorsport boss Mario Theissen said: "We are not happy - and saying we I mean BMW as well as Williams. We are not happy with the position and competitiveness we have at the moment and we have to talk about how to fix that."
It is widely accepted in F1 that BMW produces the most powerful engine but that it has been let down in recent years by Williams' cars.
This year's FW25, which was expected to be a big step forward, has been a particular disappointment.
And BMW engineers have pinned up a picture of a tortoise to a wall in their F1 truck in a swipe at Williams, according to a report in the Daily Mirror.
The photograph, displayed at the Spanish GP two weeks ago, displayed the caption: "Caught at a secret test - new BMW-Williams FW25B."
Theissen added: "We are currently talking about how the team has to be structured and organised in order to get to the top.
"This is, I think, quite a constructive process and I am confident that at the end of it we will have a constructive result."
He said BMW's principle wish is to make its partnership with Williams successful enough to challenge for the world championship.
But he did not rule out taking another route.
"We certainly have several options but our first option and priority would be to extend our partnership with Williams. But, if we do that, we want to be successful, and at the moment we are not in the position we want to be."
Theissen said BMW had ruled out quitting the
sport and had three other options: to go it alone, to forge another alliance or to renew the deal with Williams.
He said staying with Williams was the most likely and progress was being made after intense discussions.
Theissen said no deadline had been set for a resolution of talks.