An Iranian newspaper reported on Thursday that an American woman had been arrested on suspicion of spying after entering the country illegally by land.
The report, which could not be immediately confirmed by officials, was published in a column in the state-owned daily Iran, which is not known for carrying accurate reports.
If verified, the arrest would further strain relations between Tehran and the West which are facing off over Iran's nuclear programme. Iran is already holding two US citizens on spying charges.
The report said the woman had entered the country from Armenia and was detained by customs guards in the town of Nordouz in northwestern Iran. An espionage device was found in her teeth, it said.
The daily named the 55-year-old woman as Hall Talayan but did not say when she was detained.
Three American hikers, two men and a woman, were also arrested in July 2009 near the Iraqi border on suspicion of spying.
The woman, Sarah Shourd, was released on bail of $500,000 in September and returned to the United States. Her two companions remain in jail awaiting trial which was postponed in November due to Shourd's absence.