The Monoprix deal, which involves the sale and leaseback of properties, follows the July sale of a 15 percent stake in Casino's property arm Mercialys. Casino is now halfway to its goal of selling 1.5 billion euros in assets by early 2019.

Casino shares have tumbled roughly 30 percent in 2018 on concerns about its debts and those of parent holding group Rallye.

Research firm Muddy Waters has raised concerns about the debts, while Standard & Poor's and Moody's have both downgraded its credit ratings.

The stock was up 1.4 percent on Monday, making it a top performer on the Paris SBF-120 index <.SBF120>, but analysts said Casino needed to do more than sell real estate assets.

Casino said it had signed a deal with an unnamed institutional investor to sell 55 properties connected to its Monoprix supermarket arm, a major contributor to the company profit. Proceeds would be received by late December.

"Casino Group confirms all of its 2018 objectives," the company said in a statement.

"Continued good operational performance and the progressive roll-out of new profitability levers will enable Casino Group to improve its retail trading profit in France in 2019 at a similar pace to 2018, including the effects of additional rents," it said.

Analysts at brokerage Raymond James, which rates the firm "market perform", said Casino needed to do more to improve its main business performance in France despite the asset sales.

Casino said last month it had rejected a tie-up approach from Carrefour, although its larger rival denied making such an offer.

Five banks granted Rallye a new 500 million euro credit line last month, while asset sales have also reduced Casino's debts.

Rating agency Moody's cut its outlook on Casino to "negative" from "stable" on Friday to reflect "the high leverage of Casino's parent company Rallye, whose debt exceeds the value of its assets" and low cash flow generation at French stores.

Casino reported net debts of around 5.4 billion euros during its interim results in July, while the company has a current market capitalisation of around 4 billion euros.

Moody's estimated the value of Rallye's assets at about 2.2 billion euros compared with net debt of 2.9 billion euros, translating into a loan-to-value ratio of 130 percent - a level which Moody's said was "unsustainably high".

Standard & Poor's pushed Casino's debt to 'BB' from 'BB+' in September, pushing it deeper into junk territory.

Casino said its deleveraging and debt-cutting plan had so far totalled 778 million euros and that it had indicative offers on more asset sales that could occur before the end of the year.

(Reporting by Sudip Kar-Gupta; Additional reporting by Dominique Vidalon, Alan Charlish; Editing by Bate Felix and Edmund Blair)

By Sudip Kar-Gupta