May 8 (GMM) McLaren has finally got to the bottom of the cause of Heikki Kovalainen's huge crash during the Spanish grand prix two weeks ago.

Engine partner Mercedes-Benz's racing chief Norbert Haug has told German publications that the left front wheel rim broke due to a production error.

It had already emerged that the brand new wheel in question had only turned a few laps out of the box before it failed.

"A formula one rim is very complicated and comprises of several different alloys. Something has apparently gone wrong," he is quoted as saying by Bild newspaper.

McLaren's wheels are externally produced by the Japanese supplier Enkei, who are believed to now be reviewing the production and testing practices for its F1 products.

The German magazine Auto Motor und Sport reports that the wheels fitted to Lewis Hamilton's car at Barcelona were from a different Enkei batch.