LONDON: Tesco, the world's third largest retailer, must return to its core values while changes to the executive team are likely, its new chief executive has said.

Speaking in a video posted to YouTube by Tesco, Dave Lewis said he would not make any "knee jerk" decisions, but that the troubled company had to get back to the core of its business, the Telegraph reported.

"We will go back to the core. We will go back to finding out what it is – be it price, service or availability – that customers need from us so that they reward us with their loyalty," he stated.

The former executive at Unilever, the FMCG giant, started his job just last Monday, a month earlier than planned, and he has been entrusted with the task of turning the troubled retailer around.

Tesco recently issued its second profit warning in two months while its market share has been falling steadily in the face of strong competition from German discounters Lidl and Aldi, which YouGov BrandIndex recently ranked as the UK's top brand.

"I get it, I understand," Lewis said. "I am not naïve to the position of the brand and the reputation. But I only see that as an opportunity. The great thing about brands is it is easy to talk but actually you change reputation by doing."

He went on to say that there would have to be changes to the senior management and that, if he needed to, he "will make those calls".

However, Lewis remained upbeat about the company's ability to change its reputation if it improves customer service and draws on the strength of its staff, 320,000 of whom work in the UK.

In a sign of his new approach, Business Insider disclosed on Monday that Lewis had emailed all the global workforce of 500,000 on his very first day, asking them to email him directly with their ideas and suggestions for improvement.

Data sourced from Telegraph, Reuters, Business Insider; additional content by Warc staff