(Adds background, Berger quotes, byline)
By Alan Baldwin
NUERBURGRING, Germany, June 27 (Reuters) - BMW and Williams have extended their Formula One partnership for another five years to the end of 2009, they announced on Friday.
They said the new extension would lead to closer integration.
"This new contract envisages enhanced integration between the two partners," said BMW board member Burkhard Goeschel in a statement at the European Grand Prix.
Frank Williams, whose team won the constructors' championship nine times between 1980 and 1997 and were runners-up last year, said: "I have every confidence that, with the structure of this new agreement, we will be able to draw from a deeper pool of BMW resource.
"When added together with the technical competence and determination to win at Williams, I believe that this relationship will yield significant dividends."
The two sides have been negotiating all year, even though the previous deal was not due to expire until the end of 2004, with the German carmaker seeking closer involvement on the chassis side while mulling over the options.
Relations appeared strained early in the season when the Williams FW25 was slowed by aerodynamics problems.
At the low point, BMW engineers put a picture of a tortoise on the inside wall of one of their trucks with a caption suggesting it was a version of the new car.
CRITICAL COMMENTS
Gerhard Berger, one of two BMW motorsport directors, also made critical comments, although he said on Friday "that was all some of the tactics".
Williams came good in Monaco on June 1, winning with Colombian Juan Pablo Montoya, and finished second and third in Canada two weeks ago.
"We are very happy that BMW has Williams as a long-term partner," said Berger.
"The season didn't start as well as we had hoped. It was difficult to keep cool and not get emotional. There were moments when we got emotional, but it was very clear that we wanted to work with them and they with us.
"They are the perfect partners for us."
The new partnership coincides with a multi-million dollar investment in facilities, including a second wind tunnel due to open in early 2004.
BMW's other motorsport director Mario Theissen said the increased co-operation will focus immediately on joint development of the drive train with gearbox.