Responding to a complaint from a reader, the ASA said the promotion gave "very low prominence" to a disclaimer stating that tokens needed to be collected for the offer and that receiving the video playing device would incur postage and packaging costs.
The ASA ruled: "The ad featured a small disclaimer, 'token collect and p&p applies'. We also noted, however, that the body of the text stated prominently 'get your MP4 video player free with tomorrow's Mail on Sunday', which, we considered, was likely to lead consumers to expect that the MP4 player was available in the Mail on Sunday.
"Because the qualifying disclaimer was of very low prominence and because it contradicted the claims in the body copy, we concluded that the ad was likely to mislead."
The Daily Mail said all its pre-promotion material and ads for the offer stated clearly that it was a token collect promotion. Despite this the advertising watchdog ruled that the ad must not appear again in its current form.
The ASA ruling added: "We told the Daily Mail to ensure future similar promotions made prominently clear that readers were required to collect tokens to respond to the offer."