With double-digit percentage sales growth at Primark contrasting with big falls in revenue from sugar, perennial speculation of a break up has resurfaced among traders and the media.
But long-serving finance chief John Bason ruled it out and said: "It will not happen on my watch,
"What I don't get from anybody is that Primark is any less of a retailer because of ownership by ABF. I think if anything Primark is the differentiated retailer because of ABF, long may that continue."
He said Primark had thrived being part of ABF. "There's so much more to do, you'd be mad to change that wouldn't you?"
Bason was speaking after Associated British Foods (ABF), whose grocery brands include Silver Spoon sugar and Twinings tea, published a trading update for its fiscal first half ending March 1,
ABF kept its earnings guidance for the 2013/14 year in spite of highlighting the strength of sterling hitting overseas results and a weak outlook for sugar among the potential headwinds it was facing.
Primark's first-half sales were expected to be 13% ahead of last year on a constant currency basis, driven by an 8% increase in space and a 4% rise in sales at stores open over a year.
Primark's operating profit margin was forecast to be higher than in the same period last year, benefiting from warehouse and distribution efficiencies as well as lower freight rates.
First-half revenue at ABF's grocery business, which also makes Ryvita biscuits, is forecast to be ahead of last year at constant currency, with improved margins.
ABF reiterated that lower sugar prices, as the market adjusts ahead of EU regime reform in 2017, would result in a substantial reduction in first half and full year revenue and profit from its sugar businesses.
Shares in the firm, 55% owned by the family of chief executive George Weston, fell 73p, or 2.4%, to 2920p.