US gambling regulators are probing claims by a man who claims a Las Vegas casino should not have let him amass a $US500,000 ($A551,967.77) debt because he was heavily drunk, officials said Friday.
Mark Johnston is suing the Downtown Grand hotel and casino - insisting he should not be liable as rules in Nevada ban casinos from allowing "persons who are visibly intoxicated to participate in gaming activity".
The 52-year-old played blackjack and pai gow for 17 hours straight during a visit to the casino just before the Super Bowl weekend last month.
He only realised how much he had lost when he woke up the next day.
The Nevada Gaming Control Board is probing this matter.
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"The Board takes these allegations seriously and will conduct a thorough investigation," Karl Bennison, head of the Board's Enforcement Division, told AFP.
Johnston, a businessman and veteran gambler, said he was drinking even before flying from Los Angeles to Las Vegas with his girlfriend, and couldn't remember anything after dinner, which is when he started gambling.
He had another 20 or more drinks while he was playing, and was so drunk that he could not read his cards, according to the lawsuit cited by the Los Angeles Times.
He racked up the huge losses because the casino gave him credit. His girlfriend went to bed while he continued gambling and was shocked to find him still playing when she woke up, according to media reports.
"What we typically see in cases like this where someone's obviously had too much to drink, a host, a pit boss is stepping in, saying, 'Hey buddy, why don't you take a break?'," Johnston's lawyer Sean Lyttle told the newspaper.
"It seems that everyone in the building was perfectly all right with my client bidding for 17 or 18 hours non-stop, just being served drink after drink," he added.
The casino did not immediately respond to a request for comment on the lawsuit.
