An American woman has been arrested in Iran on charges of spying, the Associated Press news agency has reported.

Authorities arrested the 55-year-old woman near the border town of Norduz, 600km northwest of the capital Tehran, after she entered the country without a visa, the news wire quoted the state-owned IRAN newspaper as saying on Thursday.

The report said that the women was carrying hidden spying equipment, without elaborating on what that equipment was or when she was arrested.

Customs police were reported to have made the arrest after the woman had travelled from neighbouring Armenia to Iran.

There are already two Americans in detention in Iran for spying allegations and illegally crossing into the country from northern Iraq.

Shane Bower and Josh Fattal were arrested in July 2009 with Sarah Shourd, who was released last September.

They deny that they were spying and the US has cast doubt that they crossed into Iran at all.

Relations between Iran and the US have been broken in 1979 as the Islamic Revolution took over power in Tehran. The two countries regularly trade espionage accusations.

Source: Agencies