Household goods giant Unilever has signed the biggest advertising deal in British history, with a four-year, �320m alliance with Carlton Communications and Granada.

The deal covers advertising for Unilever's huge range of products, from Dove soap to Hellmann's mayonnaise to Wall's ice cream.

The contract exemplifies the determination of major consumer goods firms to cut costs by bundling advertising into long-term deals.

But while Unilever will effectively have negotiated a substantial discount on airtime, it also represents a shot in the arm for the two broadcasters.

Carlton and Granada have been hit hard by the advertising slump and the failure of interactive joint venture ITV Digital, and both are due to unveil dismal results this week.

'A good deal'

Neither side was willing to elaborate on the terms of the deal.

"It gives us a good deal for the money," Unilever spokesman Trevor Gorin said.

Anglo-Dutch Unilever is Britain's top advertiser, spending more than �120m on promoting its brands.

This is the first time it has signed a multi-year deal, replacing a previous system of renewable annual contracts with the broadcasters.

Carlton and Granada, Britain's biggest commercial broadcasters, will be happy to offer a discount on their usual rates in order to lock in revenues from Unilever.

The two have been the subject of persistent merger rumours, especially since the advertising market turned sour a year ago.