(CNN) -- The U.S. State Department is looking into reports that an American woman was arrested on spying charges last week when she tried to enter Iran from Armenia.

"We have asked the Swiss, who are our protecting power in Iran, to please obtain as much information as possible as soon as possible to report to us whatever facts they can determine," Secretary of State Hillary Clinton said.

Mark Toner, State Department spokesman, told reporters on Thursday there are different news stories about what happened. He said the United States is also reaching out to authorities in Armenia.

"There are lots of conflicting reports swirling about," Toner said.

Toner said U.S. officials aren't sure whether the person is an American.

Citing Iranian authorities, the semi-official Fars News Agency reported Thursday that Iranian customs officials arrested a 55-year-old American woman on charges of illegal entry and espionage.

The officials identified the woman as Hall Talayan. They said she entered Iran from Armenia without a visa and security forces discovered "'espionage devices,' such as a microphone implanted in her teeth," Fars reported.

Citing an informed Iranian official, Fars said the woman asked authorities not to return her to Armenia because she feared for her life there.

She was detained in Nordouz, a border town in northwestern Iran, Fars reported.

Other media outlets also have reported the arrest.

But Al-Alam TV, an official Iranian news agency, cited an informed source in Tehran who said the woman is in Armenia and didn't enter Iran. The outlet reported that the woman was denied entry into the country because she did not have an entry visa.

In July 2009, three Americans were detained in Iran for spying after they allegedly strayed across an unmarked border while hiking in Iraq's Kurdistan.

One of them, Sarah Shourd, was released from an Iranian prison last September on humanitarian grounds. Fellow hikers Josh Fattal and Shane Bauer are still in prison.

Two German journalists, identified only as a reporter and photojournalist, were arrested in Iran in October and charged with espionage after they interviewed the son and lawyer of Sakineh Mohammadi Ashtiani, who was convicted of adultery in 2006 and sentenced to death by stoning.