Woolworths staff are being subjected to increasing abuse after a decision not to stock Australia Day merchandise, forcing the supermarket giant to take out full-page newspaper ads explaining the move.

Earlier in January the retailer revealed it would no longer stock the public holiday paraphernalia on its shelves due to declining sales, prompting backlash from some and even calls for a boycott from Opposition Leader Peter Dutton.

Since then two stores have been vandalised with pro-Australia Day graffiti and, according to Woolworths chief executive Brad Banducci, there has been a 50 per cent increase in the number of acts of rudeness or aggression to workers.

“It’s critically important that any frustration is expressed towards me and the executive and that it’s not to our hard-working team in stores,” he told ABC radio on Wednesday.

“We could have done a better job of landing our message more clearly at the beginning and therefore, I felt it was appropriate to come back out and reiterate our message and be very clear.”

Mr Banducci reiterated that sales of Australia Day merchandise had been slipping for a number of years and the space they had taken up on shelves had already begun to shrink.

Mr Banducci has personally received more than 3000 emails from members of the public since the decision.

Despite the backlash, he said there were “not really” any signs of a Woolworths boycott.

“But that is not our real focus, our real focus is how our team feel, how our customers feel and what happens in our stores,” he said.

Other retailers including Aldi and Kmart have also revealed they will not stock Australia Day merchandise, but rival supermarket chain Coles will continue to sell the items.