A Russian journalist arrested in Tehran last week was taken into custody over alleged visa violations, Iran's government spokesman said on Monday.
Yulia Yuzik, 38, was apprehended at a hotel in the capital on Thursday, according to Russian media reports citing her ex-husband Boris Voitsekhovskiy, who is also a journalist.
At the time, a spokesman for the Russian embassy in Tehran said she was "accused of working for Israeli secret services".
But Iran's government spokesman Ali Rabiei denied on Monday that she was held for alleged espionage.
"As far as I know, the case is about this lady's crimes regarding visas and other crimes," Rabiei told a news conference in Tehran.
"The case is not related to counter-espionage," he said in remarks aired live on state television, adding that "it is being dealt with swiftly".
Russia summoned Iran's ambassador to Moscow to seek clarifications over her arrest and to ensure the rights of the journalist are observed.
Yuzik has worked for a number of publications, including the Russian version of Newsweek.
She has authored two books, including "Beslan Dictionary", which is based on testimony from survivors of the 2004 Beslan school massacre that claimed more than 330 lives, more than half of them children.