Alonso joined McLaren after winning the championship the past two years with Renault. He clashed with management and teammate Lewis Hamilton throughout the season, and finished behind champion Kimi Raikkonen of Ferrari and Hamilton.

"Since I was a boy I had always wanted to drive for McLaren, but sometimes in life things do not work out," Alonso said in a statement.

Alonso, who still has a two years left on his contract, reached an agreement that allows the driver to leave without penalty.

"(We) want to wish Fernando all the best for the future," McLaren team boss Ron Dennis said. "He is a great driver but for some reason the combination of (our team) and Fernando has not really worked out, and in the end we reached a stage where none of us could find a way to move forward."

Alonso has been linked with a possible return to Renault or a move to Williams or Red Bull.

Alonso had complained that as a world champion he deserved preferential treatment, and accused McLaren of favoring the 22-year-old rookie Hamilton. Dennis and Alonso didn't talk to each other for a period.

"I know there have been suggestions of favoritism within the team and people say a lot of things in the heat of battle, but in the end I was always provided with an equal opportunity to win," Alonso said. "Yes, we have had our ups and downs during the season, which has made it extra-challenging for all of us, and it is not a secret that I never really felt at home."

Alonso was one of the drivers whose name was involved in the spying scandal that overshadowed the second half of the season.

McLaren was fined a record $**0 million by the World Motor Sport Council on Sept. 13 after FIA found the team guilty of using leaked data from Ferrari. The British team was kicked out of the constructors' championship, and authorities contended that Alonso had some knowledge of the facts.

"We all believe that our joint decision to part company is for the best, and we will now continue to focus on our 2008 world championship challenge," Dennis said.