Williams will see many changes at the end of the season

The American firm has been the Oxfordshire-based outfit's major backer for the last five years.

The news, though expected, adds to uncertainty at Williams, who are parting company with engine suppliers BMW and moving to Bridgestone tyres.

On top of that, Jenson Button is in talks to escape his contract at Williams in 2006 so he can stay at BAR.

Are we witnessing the beginning of the end for Williams? From Ricky Have your say on Five Live

Hewlett-Packard executive vice-president and chief marketing officer Cathy Lyons said the partnership with Williams had been a success.

"We have met our objectives and it is a natural moment for HP to conclude our relationship," said Lyons.

"We wish them all the best as they go in a new direction next season."

HP cuts 968 UK posts

Hewlett-Packard is set to cut 968 jobs in the United Kingdom during the next year as part of its worldwide restructuring drive.

The company announced in July that it would cut 14,500 jobs globally over 18 months in order to save �1.1bn a year.

The cutbacks are the largest at the company since 15,000 jobs were lost in the wake of Hewlett-Packard's $19bn acquisition of rival Compaq Computer in May 2002.