BMW motorsport director Mario Theissen has urged champions Ferrari to join other Formula One teams in limiting testing next year.

"I certainly hope they will join because it absolutely makes sense to restrict testing," Theissen told reporters at a motorsport industry conference in Frankfurt.

"If you look at the mileage we cover during a year, 80 percent of it is testing, 20 percent is practicing and racing."

Nine of the 10 teams, including BMW's partners Williams, reached a voluntary agreement at a meeting in London this week to halve the amount of testing carried out next year to 24 days during the season.

However Ferrari, constructors' champions for the past six years, did not attend the meeting and have resisted attempts in the past to reduce testing.

Formula One's rules are changing next year, with engines having to last for two race weekends rather than one -- an increase from 800 km per engine to 1,500.

"You need a lot of engines to cover that amount of mileage and the engine is the most expensive part of the car, so restricting testing is a very good way to cut costs, and this is why we support it," said Theissen.

"We would certainly not be the first team to run out of money but it absolutely makes sense and it doesn't make sense to waste money."

"Covering 80 percent of the mileage at the test tracks means hiding the show from the spectators."

While BMW have in the past ruled out supplying another team with engines, Theissen suggested it might be possible with reduced testing.

"That would be possible," he said. "It isn't our intention at the moment but from the capacity side it would become possible."

Formula One's governing body, the International Automobile Federation (FIA) have announced further engine changes from 2006 with the capacity reduced from 3.0 litre V10s to 2.4 litre V8s, a move opposed by BMW.

BMW, Mercedes and Honda have raised the prospect of taking the FIA to arbitration over the changes but Theissen said no decision had been taken.

"We still are (in talks). We are in very intense discussions this week and probably next week and by then we should know what to do about it," he said.

But he endorsed other cost-cutting measures.

"We should review the amount of money spent and check if it's really contributing to the show," he said.

"We want to see Formula One being a strong and stable racing series in 10 years and to achieve that it has to be worth the money spent. And that's why we're absolutely joining the cost-cutting measures.

"We have entered this sport on the basis of the current situation so we are prepared to spend the money it takes to be top in Formula One today," added Theissen.

"But we think it's absolutely reasonable to review the cost and to cut it."