Hot property Rosberg (left) says he is happy at Williams

Williams said: "It was an offer of majestic proportions, but it was never ever discussed or entertained.

"Why give away the crown jewels? Why improve the car by one second and give away half a second with the driver?"

McLaren eventually signed Finland's Heikki Kovalainen from Renault in mid-December to partner Lewis Hamilton.

Rosberg, the son of Finland's 1982 world champion Keke, had earlier signed an extension of his Williams contract to take in the 2008 and 2009 seasons.

Williams added: "I was a little surprised he was happy to sign to stay. I feared he would go to McLaren."

606: DEBATE Was Rosberg right to reject McLaren's advances?

Rosberg, 22, said: "I'm happy where I am. If the money is okay, and everybody is happy, then a contract still means something.

"I know Frank has never thought of letting me go, so it makes me feel good to be wanted."

Meanwhile, McLaren have reacted strongly to reported Italian police claims that high-ranking team employees have "responsibility" for the F1 spy saga.

A police statement has suggested that evidence taken from McLaren's HQ and the homes of top executives implicates high-level McLaren figures in the case.

Dennis's team are desperate to put the spygate row behind them

An excerpt was published in Italian sports daily La Gazzetta dello Sport.

But McLaren described the wording of the statement, as seen in the paper, as "grossly inaccurate and misleading".

The team objected to a passage which claimed that from the evidence gathered, there "clearly emerges the responsibilities of the management and some technicians at a high level in McLaren".

In a statement, the team said: "McLaren Racing wishes to record its extreme displeasure with the wording of a statement that the Italian police are reported to have made.

"The reports incorrectly claim that the searches produced material which clearly shows the responsibility of certain people at McLaren Racing.

"In fact, the Italian police have not yet even been given access to any of the material taken, nor have they even started to review that material."

McLaren were fined �50m and stripped of all their 2007 constructors' points by the sport's governing body the FIA for their involvement in the spy row.