Lidl UK boss Ronny Gottschlich has left the discounter with immediate effect and been replaced as chief executive by Christian Härtnagel.

The reasons behind Gottschlich’s shock departure from the retailer are unclear, with Lidl refusing to confirm or deny whether he had another job lined up.

Härtnagel, who joined Lidl in 2003, takes the top job at the age of just 34 having spent 13 years with the business.

He has held various management positions across the business, including regional director at Lidl Ireland, and was most recently responsible for sales and operations for Lidl Austria in his role as a board director.

Gottschlich has spearheaded Lidl’s rapid growth in the UK – where it has more than 630 stores – since taking over as chief executive six years ago.

He was handed a 56% pay rise in 2015 after the grocer’s annual sales hit £4.7bn.

Gottschlich joined Lidl in 2000 and has held positions including national audit manager, regional director and operations director in Germany and Austria, as well as the UK.

He was handed the top job at Lidl’s British business in September 2010.

Gottschlich has helped Lidl become the fastest growing grocer in the UK – according to Kantar Worldpanel data – having overtaken its great rival Aldi.

The duo have shaken up Britain’s food retail sector, wooing shoppers from the big four with rock-bottom prices and the quality of its own-label ranges.

In July last year, it unveiled plans to build a new 220,000 sq ft UK head office in Tolworth, with staff expected to begin moving into the new headquarters at the end of 2018.