* Casino to sell 58.6 pct stake for $3.5 bln excluding debt
* Casino's asset sales are part of its plans to cut debt
* Deal to boost tycoon Charoen's retail presence in Thailand (Adds confirmation and details of the deal from Casino)
By Denny Thomas and Khettiya Jittapong
HONG KONG/BANGKOK, Feb 7 (Reuters) - France's Casino Group has agreed to sell its majority stake in Thai hypermarket operator Big C Supercenter for 3.1 billion euros excluding debt ($3.5 billion) to Thailand's TCC Group, it said on Sunday.
The deal is a part of the French food retailer's debt reduction plan. Casino announced a 4-billion-euro disposal plan in 2016, including the sale of its Vietnam unit and its stake in the Thai hypermarket chain.
Casino's plan to sell the Thai unit came after a December report by short-seller Muddy Waters that said the French firm was "dangerously leveraged", prompting its worst stock slide in seven years. The Vietnam unit sale had been planned earlier.
The sale to TCC - controlled by Thai tycoon Charoen Sirivadhanabhakdi - will allow Casino to reduce its debt by 3.3 billion euros and will be completed by March 31, the French retailer said in a statement.
The transaction values Big C at 252.88 baht ($7.1) per share, Casino said. This is a 28 percent premium to Big C's share price on Jan 14, when Casino announced the sale of its stake, and around 11 percent more than the close on Friday.
The Big C deal would make for Thailand's second-biggest inbound acquisition after 2013's $6.6-billion purchase by CP All PCL of cash-and-carry wholesaler Siam Makro Pcl.
It was not clear whether Central Group, which was also bidding for Casino's stake, would sell its 25 percent holding in Big C, a retailer it originally founded in 1993 and then sold a majority stake to Casino in 1999.
Central declined to comment on the matter. TCC was not available for comment.
Ratings agency Standard & Poor's last month put Casino's debt on "negative watch" for a possible downgrade to junk status, citing concerns over the retailer's high debt pile and weakness in its Brazilian market.
Big C is Thailand's second-largest hypermarket operator after Tesco's Thai unit, and has a market capitalisation of 163.25 billion baht ($4.60 billion).
Charoen's acquisition of Big C would boost the tycoon's retail presence in Thailand. He owns Berli Jucker PCL, the listed retail arm of TCC.
$1 = 35.5200 baht $1 = 0.8961 euros Additional reporting by Sybille de La Hamaide in PARIS, Manunphattr Dhanananphorn and Amy Sawitta Lefevre in BANGKOK; Editing by Himani Sarkar and Mark Potter