Iceland suffered a fall in sales during the crucial festive trading period despite the impact of its Christmas advert.

In a note to bondholders seen by the Financial Times, the frozen-food specialist said like-for-like sales were down 1% in the 16 weeks to January 4.

Total sales during the period, which included the impact of new store openings, increased 3.5%.

Iceland’s founder Sir Malcolm Walker had warned before Christmas that trading had been sluggish.

The grocer declined to comment further on its sales figures or the bondholder report this morning.

Iceland generated a tidal wave of publicity from its ‘Rang-Tan’ Christmas advert, which focused on its decision to remove palm oil from its own-brand products.

The ad was banned from being aired on TV, but has clocked up more than 70 million views on social media, including six million through Iceland’s official YouTube channel.

Clearcast, which passes adverts as being legally compliant, did not approve the ad because it had been made by Greenpeace and political advertising is not allowed on UK television.