The boss of Primark has admitted an “error of judgment” and resigned following an allegation made by a woman about his behaviour towards her in a social environment, the retailer’s owner has said.

Associated British Foods (ABF) said on Monday that Paul Marchant cooperated with an investigation it initiated, accepted that his actions fell below the standards it expected and resigned with immediate effect.

The company said Marchant had made an apology to the individual, the ABF board as well as “his Primark colleagues and others connected to the business”.

George Weston, the chief executive of ABF, said: “I am immensely disappointed. At ABF, we believe that high standards of integrity are essential. Acting responsibly is the only way to build and manage a business over the long term.

“Colleagues and others must be treated with respect and dignity. Our culture has to be, and is, bigger than any one individual.”

The group said it would continue to offer support to the individual who brought this behaviour to its attention.

Marchant joined Primark as chief operating officer in 2009 and became chief executive later that year, taking over from Primark founder Arthur Ryan. He previously worked for Debenhams, Topman, River Island and New Look.

“As we have committed to publicly, ABF seeks to provide a safe, respectful, and inclusive work environment where all employees and third parties are treated with dignity and respect. Primark is committed to doing business the right way at all levels of the company,” the group said.

Eoin Tonge, ABF’s finance director, will act as Primark’s chief executive on an interim basis, with its group financial controller, Joana Edwards, becoming interim finance director.