Bruce Willis was caught in an alcohol-fueled meltdown during a trip to Paris and had to be escorted out of a hotel bar by two hotel employees!

The wild partying is a concern because Willis went through Alcoholics Anonymous years ago and has long insisted that his drinking days are behind him.

And the danger is that once a person is addicted to alcohol, the addiction can quickly return when the person begins drinking again, Dr. Wilkie Wilson, professor of pharmacology at Duke University School of Medicine, told The ENQUIRER.

“Addiction to a drug is a very long-lasting process in the brain.”

An ENQUIRER investigation found that Bruce had already been partying before he arrived at the Ritz hotel’s bar on March 20 with his very much-younger girlfriend Brooke Burns.

“While Willis was not falling-down drunk, he seemed to stagger when he walked into the bar with Brooke,” a source in Paris revealed.

“Later, around midnight, he began to order shots of hard liquor.

“The intimate, wood-paneled Hemingway Bar is usually frequented by elderly millionaires enjoying a last brandy and cigar before bed.

“But Willis outraged the well-heeled clientele when he started singing loudly and openly groped Brooke on one of the bar’s banquettes.

“He was tipping drinks down and fondling his girlfriend so blatantly that other people didn’t know where to look.

“Then he took his hat and began passing it around, demanding that customers put some money in it for the barman. When people ignored him, he started hammering on the counter, demanding cash.”

According to a published report, it was at this point, about half an hour after he came in, that the hotel staff decided they’d had enough. The report claimed Bruce and Brooke were then led out of the bar by two hotel employees.

The 49-year-old actor had started partying six hours earlier at the 29th birthday party of French rock star Johnny Hallyday‘s wife Laetitia at the trendy Paris restaurant Ginger, the source disclosed.

“Others at the birthday party included French actor Jean Reno and French president Jacques Chirac‘s daughter Claude.”

Willis’ night on the town in Paris was shocking because the star has repeatedly said in the past that he’s on the wagon. Willis now says that he has been a “social drinker” for a number of years.

Willis has credited “Die Hard” producer Joel Silver with getting him off the bottle — the deal was that Silver would give him the movie role of Det. John McClane if he would agree to give up his wild living.

He underwent counseling and attended Alcoholics Anonymous sessions in Los Angeles. In 1989, he proudly told a reporter: “I haven’t had a beer in two years.”

In 2001 Willis again told an interviewer that he doesn’t drink. And as recently as 2003, he said of his drinking: “That has all been over for years.”

An attorney for Willis told The ENQUIRER that while Willis was at the Paris bar, “he was not falling down or staggering” and that “contrary to what was written about him being escorted out, Bruce left on his own with Brooke.

“In fact, the hotel has apologized to my client’s publicist — saying they are sorry a false report was published about Willis being escorted out of their bar.”

Top Beverly Hills psychiatrist Dr. Carole Lieberman said Willis’ renewed drinking may stem from the pressure of trying to keep up with his girlfriend Brooke, who at 26 is 23 years his junior.

Dr. Lieberman, who is not treating Willis, told The ENQUIRER: “He probably feels that if he’s not drinking and getting wild, his girlfriend is going to feel like he’s a dud!” — JIM NELSON and PATRICIA SHIPP