Rapists and other offenders convicted of the most serious sex crimes have been able, for the past several years, to get the erection-enhancement wonder drug Viagra for free through Medicaid, the government-financed health-insurance program for the poor.

According to the state comptroller, Alan Hevesi, who announced the finding yesterday, 198 Level 3 sex offenders in the state, who have been convicted of such crimes as child molestation and rape, had Viagra prescriptions subsidized by the state between January 2000 and March 2005.

A federal directive seven years ago that Medicaid pay for Viagra prescriptions for eligible male adults did not carve out an exclusion for convicted sexual offenders.

The comptroller’s tally of 198 does not count lower-level sex offenders or the less-noted erectile-dysfunction drugs Levitra and Cialis, which have become popular Viagra alternatives and are also covered by Medicaid.

When those factors are considered, New York could be subsidizing the medications for thousands of sex offenders, Mr. Hevesi said.

“The whole purpose of Viagra, and now Cialis and Levitra, other drugs that perform the same function, is to increase sexual function, to increase libido, to increase blood flow, to increase the capacity of the user of the medication to perform sexually,” Mr. Hevesi said during a news conference at his Lower Manhattan office.

“The bottom line is that this is a category of patients who should not be receiving these drugs,” the comptroller said.

The practice dates back to a 1998 federal mandate that all states cover Viagra – one of Pfizer’s biggest moneymaking and most heavily advertised drugs – for male Medicaid recipients if a doctor determined that it was needed.

Mr. Hevesi and Senator Schumer, who joined him for the announcement yesterday, said they believed the loophole related to sex offenders was an “unintended consequence” of an otherwise sensible idea, but that it needed to be closed immediately.

“It is just mind-boggling to think that Level 3 sexual offenders can get Viagra, which may indeed help them perpetrate further horrible crimes,” Mr. Schumer said.

“Our first job has to be to defend potential victims,” the senator said. “To say that they would be able on the federal, state, and local governments’ arm to get Viagra for free” does not make sense.

The comptroller said his office began looking into the matter after receiving a tip, though he would not elaborate on where the lead came from. His office then electronically matched the Level 3 sexual offenders list, which is available publicly, to a list it teased out from Medicaid.

Level 3 offenders, who number nearly 7,400 statewide, are deemed the most dangerous, based on a combination of factors, including the nature of their crimes and the extent to which they are considered to pose a risk upon release from prison or jail. Level 1 and 2 sexual offenders are not required to register with a public database, so their names could not be cross-searched.

Mr. Hevesi called on the secretary of the federal Department of Health and Human Services, Michael Leavitt, to change the regulation immediately. Officials from the federal department could not be reached for comment yesterday.

A spokeswoman for Governor Pataki, Jennifer Meicht, said during a phone interview that the governor supported an immediate change in the federal regulation to address the problem.

“We would hope that the federal government would take action to rein in this waste of taxpayer dollars,” she said. “The governor has been a strong advocate for tougher penalties for sex offenders and has supported proposals that would make it easier for parents to protect their children from sexual offenders in the community.”

In addition, the comptroller’s office included a statement from the speaker of the state Assembly, Sheldon Silver, in its new release.

“This probe makes it crystal clear that combating sex crimes requires vigilant, comprehensive solutions,” Mr. Silver, a Democrat of Manhattan, said. “There is no excuse for allowing Level 3 sex predators, the absolute worst of the worst, to have Viagra.”

Mr. Schumer said that if the federal government “dillydallied,” he would introduce legislation to make the necessary changes, not just in New York but nationally.

State Medicaid recipients received 358,000 Viagra prescriptions in 2004 for a cost of $21.3 million, according to the comptroller’s office. Mr. Hevesi estimated that the 198 sexual offenders accounted for $85,000 of that.

He also guessed that more than half of them live in New York City, though he was basing that on the standard Medicaid breakdown.

Amending the regulation to notify doctors when sex offenders request Viagra was one potential solution mentioned yesterday. Mr. Hevesi said doctors are probably unaware of a patient’s criminal history when prescribing the drug.

A spokesman for Pfizer could not be reached yesterday.

The company Web site says the drug has been prescribed to approximately 23 million men worldwide, and reports indicate that it has netted the company more than $1 billion.