WASHINGTON — Sex workers seeking free condoms scooped up as many as 5 million last year from distribution vans that prowl Washington, D.C. streets, an effort the city's health department says helps explain a reduction in new AIDS cases.

But police in Washington may be undermining that work by targeting suspected prostitutes based on how many condoms they're carrying, according to a city health official and a human rights group.

Human Rights Watch released a report Thursday that describes widespread talk among sex workers in Washington - and also New York, San Francisco and Los Angeles - of a "three condom rule," meaning that being found with three or more condoms invites almost certain arrest.

Such practices "discourage people from using condoms, which means it puts people at greater risk," said Michael Kharfen, who manages the District health department's condom distribution program.

"Our position is that public safety includes public health," said Megan McLemore, a senior health researcher with New York-based Human Rights Watch and the report's author.

McLemore called targeting suspected prostitutes by counting condoms "a backward practice," adding, "These are very vulnerable people engaging in very high-risk behavior. They should definitely be using condoms."

Metropolitan Police Department Assistant Chief Peter Newsham denied that officers are using condom counts as a pretext to target suspected prostitutes, and said to do so would be wrong.

Kharfen said complaints about the practice surfaced years ago but had been mostly alleviated after talks with police - though some complaints had resurfaced recently.

He stopped short of accusing officers of using the tactic, but said his office has been talking with police commanders to make sure that if it's happening, it is stopped.

"Our aim is that condoms are not part of the conversation with respect to prostitution," said Kharfen. "We are happy that people have condoms. We are trying to get a lot of condoms into the community."

Newsham, who is quoted in the Human Rights Watch report, said he doubts officers are counting condoms, but he said "it would be improper" if they were. He called the Human Rights Watch report more anecdotal than factual, "without any real data to support it."

"We stop someone based on reasonable suspicion and we search based on probable cause," said Newsham. "It's 100 percent legal to carry condoms, as many as you want."

Newsham dismissed the three condom rule as street lore.

"There is no such thing," he said, adding that the only time condoms would be used in court would be in a brothel bust, where officers might find hundreds or even thousands, which could help establish a large-scale operation.

Stings targeting prostitutes, Newsham said, are rarely carried out in the District and are generally prompted by complaints from residents or community groups.

Noting the millions of condoms distributed in the District last year, Newsham said, "It doesn't seem like people are reluctant to take them. . . . To somehow suggest that the police department is contributing to AIDS is a disservice."

Kharfen said he understands the concerns of residents angry when prostitutes operate near their homes, and agrees that police need to act.

But "condoms are not illegal," he said. "There is no provision in the law that says there is a limit to how many you can have. They are a medical device."

One Washington sex worker said that being caught with more than three condoms and more than $20 "is a problem."

"I know a great many people that aren't using condoms. They want to stay away from the cops," said one transgender sex worker, 42, who agreed to an interview on the condition of anonymity to protect her privacy.

The sex worker is a client of the group Helping Individual Prostitutes Survive, which provided her contact information to a reporter. The organization runs a van service that last year distributed about 850,000 condoms to Washington sex workers.

"We know people are going to have sex with or without" condoms, said Cyndee Clay, the group's executive director. "We just hope they have sex with them. Condoms are not what's driving sex in the city, or prostitution. Nobody walks up and says, 'Hey, I have a bag full of condoms. Let's do sex work.' "

The Human Rights Watch report was released at a news conference at the National Press Club ahead of the International AIDS conference, which begins Sunday in Washington. Human Rights Watch is also investigating whether D.C. police covered up and misreported sexual assaults.

Researchers on the condom report said they spoke to more than 300 people - including 200 sex workers, law enforcement authorities and social workers - in four cities hit hard by HIV and AIDS. Even with a 32 percent reduction in new AIDS cases in 2010, Washington has one of the highest infection rates in the country. About 14,465 residents - 2.7 percent of the population - live with HIV, according to a report issued this month by the health department.