When do the blinds go up?

[Trantor]

The bell goes to indicate the blinds are to go up to the next level. To which blinds does the increase apply? To the next blinds to be placed if the first card of the new round has not yet been dealt, to the blinds of the current round if the cards for the round have been dealt but the small blind hasn't yet posted, or when?

The former seems appropropriate but I can't find any rule on the point.

Thanks

Trantor