UK drugs company GlaxoSmithKline has been accused of creating a "serious public health concern" by regulators over its labelling of hepatitis and flu vaccines in the US.

The food and drug administration, the American regulatory body, sent a warning letter to the firm over its actions this month. It said it had given "false and misleading" information about who should take flu vaccines during the peak winter season, and also did not detail the risks of taking the vaccines Engerix-B, against hepatitis B, Havrix (hepatitis A) and Twinrix (both viruses).

It ordered the firm to correct the information and send it to all those who had seen the false promotional material, "because the violations described above are serious".

The warning letter is particularly embarassing for the firm at a time when it is being sued by New York state attorney general Eliot Spitzer over its handling of clinical trials for Seroxat, the antidepressant. It is alleged that GSK hid negative information about its safety and effectiveness.

According to the FDA, a summary of information on hepatitis vaccines distributed by Glaxo said it was safe to give flu vaccines to children between six months and five years old and to pregnant women, which is not true. It also failed to reveal safety information about the hepatitis vaccines, such as adverse reactions like fatigue and headaches and failed to warn about potential sensitivity to yeast and the antibiotic neomycin which is in some of the vaccines.

"The summary [of immunisation information] creates a serious public health concern because it could lead to incorrect administration of the live attenuated influenza vaccine to individuals, including pregnant women with medical conditions and children from six months to up to five years old, for whom that product has not been demonstrated to be safe and effective," the letter said. "In addition, this summary was distributed during the height of the flu season with false and misleading in formation regarding the live attenuated influenza vaccine."

The FDA routinely sends warning letters to firms in the drugs trade but rarely issues such a strong rebuke to the big pharmaceuticals firms. In 2002 it issued a warning to Glaxo over manufacuturing processes in two Puerto Rican factories, and it is still investigating.

GlaxoSmithKline did not return calls for comment at the time of going to press.