CBS is managing to charge advertisers double the rates of a year ago for short-notice bookings, it said on Thursday, adding that it was cancelling promotions for its own shows to squeeze more ads on to the US broadcast network behind CSI and David Letterman.

Advertisers were “knocking down the door”, Les Moonves, CBS chief executive, told analysts on a conference call to discuss third-quarter earnings that showed continued pressure on sales and profits but some recovery in profit margins.