WASHINGTON (AP) — The Food and Drug Administration issued warning letters Wednesday to four manufacturers of alcoholic energy drinks, saying the caffeine added to their beverages is an "unsafe food additive."

FDA Commissioner Margaret Hamburg said the combinations of caffeine and alcohol in the drinks is a public health concern and can lead to "a state of wide-awake drunk." Evidence has shown their consumption has led to alcohol poisoning, car accidents and assaults, she said.

The government can seize the products if the companies continue to make them.

Several college students have been hospitalized in recent months after consuming the drinks. The FDA said experts have raised concerns that the caffeine in the drinks can mask a person's feeling of intoxication, leading to risky behavior.

In response to such incidents, four states — Washington, Michigan, Utah and Oklahoma — have banned the beverages. Other states are considering similar action.

Phusion Projects, which manufactures Four Loko, announced late Tuesday that it would reformulate its drinks, removing caffeine.

The company's statement said it was removing caffeine from the drinks after unsuccessfully trying to deal with "a difficult and politically-charged regulatory environment at both the state and federal levels."

"We have repeatedly contended — and still believe, as do many people throughout the country — that the combination of alcohol and caffeine is safe," said Chris Hunter, Jeff Wright and Jaisen Freeman, who identify themselves as Phusion's three co-founders and current managing partners.

Four Loko comes in several varieties, including fruit punch and blue raspberry. A 23.5-ounce can sells for about $2.50 and has an alcohol content of 12 percent, comparable to four beers, according to the company's website.

The FDA said it views Phusion Projects' announcement as a positive step, but officials said they have not yet heard directly from the company about its timeline for taking the drinks off the market. The FDA also issued warning letters to Charge Beverages Corp., New Century Brewing Co. and United Brands Company Inc.

Last year the FDA notified more than two dozen manufacturers of caffeinated alcoholic beverages that it never had specifically approved the addition of caffeine to alcoholic drinks and began studying whether it was unsafe and should be outlawed. The agency noted the mix's growing popularity among college students and its potential health and safety issues.