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Ask Siri, Apple’s virtual assistant for the iPhone, for ideas on where to eat dinner or whether you need an umbrella, and it will deliver helpful localized suggestions.

But try asking it to find a local abortion clinic, and the software turns up a puzzling blank — even in areas that clearly have such clinics. The response in Manhattan is: “Sorry, I couldn’t find any abortion clinics.”

This is, of course, not a question that most people are likely to be asking their phones. But the odd results began to attract attention around the Web on Tuesday, with some suspecting a conspiracy.

“I can’t help but feel that something is rotten in the state of Denmark,” said one blogger at a site called The Abortioneers.

Megan Carpentier, the executive editor at a blog called The Raw Story, noted that Siri users in the Washington area are directed toward antiabortion pregnancy centers in Virginia and Pennsylvania — not the nearby Planned Parenthood. Asking Google the same question turned up ads for seven abortion clinics, two pregnancy centers and an abortion referral service.

Apple did not immediately respond to a question about the results. But Norman Winarsky, who runs a research and investment firm called SRI Ventures and was one of the founders of Siri before Apple bought it in 2010, said in an interview that at its core, Siri works by translating a spoken request into text, singling out keywords and then using various Web services to suggest answers.

Mr. Winarsky was quick to say that he had no knowledge of what modifications Apple might have made to Siri after acquiring it, or what third-party services the company might be using to generate its Web results. He said it was not clear whether Siri’s inability to produce answers to specific queries was a deliberate decision on Apple’s part.

“Those answers would be coming from the Web services that Siri is connecting to, not necessarily Apple,” he said. “My guess at what’s happening here is that Apple has made deals with Web services that provide local business information, and Apple probably hasn’t paid much attention to all the results that come up.”