Iran has dismissed as "lies" US media reports suggesting that an American citizen it recently arrested is being held in suboptimal conditions.

"An American citizen named Michael White was arrested in the city of Mashhad a while ago and the US Interests Section in Tehran was informed in the first days" since his arrest, Iran's Foreign Ministry spokesman Bahram Qassemi told reporters Wednesday.

The New York Times reported Monday that White, a US Navy veteran, had been arrested in Iran on "unspecified charges."

In another report on Tuesday, CBS News claimed the 46-year-old had been in detention since last summer and "was suffering psychologically and was being held in a ward with dangerous criminals."

Qassemi said, "We strongly reject such untrue and false reports."

The US State Department confirmed that it had been informed of White's arrest but refused to provide more details.

“We are aware of reports of the detention of a US citizen in Iran. We have no higher priority than the safety and security of US citizens abroad. Due to privacy considerations, we have no additional information to provide at this time,” a State Department official told the Times via email.