BANGOR, Me.  For years, the location of this city’s needle exchange program, in a nondescript strip mall close to highways and bus lines, was seen as a major asset.

But now, AIDS activists say, that very location could undermine what happens inside the exchange.

A bill working its way through Congress would lift a ban of more than 20 years on using federal money for needle exchange programs. But the bill would also ban federally financed exchanges from being within 1,000 feet of a school, park, library, college, video arcade or any place children might gather  a provision that would apply to a majority of the country’s approximately 200 exchanges.

“This 1,000-foot rule is simply instituting the ban in a different form,” said Rebecca Haag, executive director of the AIDS Action Council, an advocacy group based in Washington. “Clearly the intent of this rule is to nullify the lifting of the ban.”

Under a separate bill, all exchanges in Washington within the 1,000-foot perimeter would be barred from receiving city money as well as federal money.