PROVIDENCE, R.I. (AP) _ Wine coolers that burned the mouths of three people were probably contaminated at the bottling plant in France with a caustic solution used to remove labels, the manufacturer said Wednesday.

Henri Berthe, a partner in Les Grande Chais de France, makers of Quenchette French Raspberry Cooler, said the contamination had been traced to a shipment of 2,500 cases of the beverage sent to Rhode Island and Vermont.

An unknown number of bottles were tainted with the cleaning solution sodium hydroxide, Berthe said from his office in Greenwich, Conn. The chemical is also used in household drain cleaners.

Earlier on Wednesday, Ed McDonnell, acting regional director of the Food and Drug Administration in Boston, said the contamination apparently resulted from an accident at the plant.

''It does not look like a tampering case at this time,'' he said.

The FDA joined the investigation Tuesday, a day after the state Health Department issued a statewide recall of the raspberry cooler. Berthe said he asked the Vermont distributor Wednesday to pull the cooler from store shelves.

McDonnell said the FDA believes the company, which is based in Strasbourg, France, used the improperly cleaned bottles only for the raspberry-flavored cooler. The company makes eight other flavors.

On Monday, the state Health Department learned that two people had suffered burns from the cooler. A third incident was reported in Woonsocket on Tuesday.

Two tainted bottles appear to have been contaminated with sodium hydroxide, but the third bottle had not yet been tested by state or federal investigators.

Berthe, who initially speculated that the product had been tampered with in the United States, said the affected shipment arrived in early July. Rhode Island received 1,346 cases; the remainder went to Brattleboro, Vt., he said.

Les Grand Chais has produced the raspberry wine cooler for 1 1/2 years and imports about 12 million bottles a year, Berthe said.