The financial terms of the acquisition were not disclosed.

Dejbox, with estimated revenues of 20 million euros (17 million pounds) for 2019, says it is the biggest online canteen supplying meals to businesses in suburban and outlying areas in France. It employs around 300 staff.

"It will give us the opportunity to expand our customer base to include employees of medium-sized, small and micro businesses and also invest in the fast-growing food delivery segment," Amélie Oudéa-Castera, Executive Director Customers, Services and Digital Transformation at Carrefour, said on Monday.

At 0815 GMT, Carrefour shares were down 2.1% at 14.71 euros in a weak European stock market.

The company is in the midst of a five-year plan to cut costs and invest in e-commerce, as well as organic and own-brand products, to try to tackle competition from the likes of domestic rival Leclerc and online giant Amazon.

"Obviously we can see some fit with Carrefour's stated strategy of catching up in e-commerce but it simply feels a step too far to be able to make a meaningful contribution to the turnaround of the core business," Bernstein analyst Bruno Monteyne said in a note.

"We would rather see progress in the core/legacy business (branded products in hypermarkets) than adding a whole new product segment for a whole new customer base," he added.

(Reporting by Sudip Kar-Gupta; Editing by Louise Heavens and Mark Potter)

By Dominique Vidalon and Sudip Kar-Gupta