AUSTIN, Texas -- Merck & Co. is helping bankroll efforts to pass state laws requiring girls as young as 11 or 12 to receive the drug maker's new vaccine against the sexually transmitted cervical-cancer virus.

Some conservatives and parents' rights groups say such a requirement would encourage premarital sex and interfere with the way they raise their children, and they say Merck's push for such laws is underhanded. But the company said its lobbying efforts have been aboveboard.

With at least 18 states debating whether to require Merck's Gardasil vaccine for schoolgirls, Merck has funneled money through Women in Government, an advocacy group made up of female state legislators around the country.

A top official from Merck's vaccine division sits on Women in Government's business council, and many of the bills around the nation have been introduced by members of Women in Government.

"Cervical cancer is of particular interest to our members because it represents the first opportunity that we have to actually eliminate a cancer," Women in Government President Susan Crosby said.

Gardasil, approved by the federal government in June, protects girls and women against strains of the human papillomavirus, or HPV, that are responsible for most cases of cervical cancer. A government advisory panel has recommended that all girls get the shots at 11 and 12, before they are likely to be sexually active.

But no state has yet to add Gardasil to the list of vaccinations youngsters must have under law to be enrolled in school.

Merck spokeswoman Janet Skidmore would not say how much the company is spending on lobbyists or how much it has donated to Women in Government. Crosby also declined to specify how much the drug company gave to the group.

But Skidmore said: "We disclosed the fact that we provide funding to this organization. We're not in any way trying to obscure that."

The New Jersey-based drug company could generate billions in sales if Gardasil -- at $360 for the three-shot regimen -- were made mandatory across the country. Most insurance companies now cover the vaccine, which has been shown to have no serious side effects.

Cathie Adams, president of the conservative watchdog group Texas Eagle Forum, said the relationship between Merck and Women in Government is too cozy. "What it does is benefit the pharmaceutical companies, and I don't want pharmaceutical companies taking precedence over the authorities of parents," she said.