Iranian media has said a US ScanEagle drone was captured "in the last few days" by the naval unit of the Islamic Revolutionary Guards Corps after entering Iranian airspace while gathering information over Gulf waters.
A US Navy spokesman said they were aware of the reports, and were looking into them.
Last month the US said Iranian warplanes shot at an American surveillance drone flying in international airspace. Iran said the aircraft had entered its airspace.
More top news
Theresa May says Monday's live TV grilling showed Jeremy Corbyn is "not prepared" to lead the country or conduct Brexit talks.
Economics have warned of drastic consequences if Prime Minister Theresa May fulfills her pledge to walk away from a "bad" Brexit offering.
Arsenal manager Arsene Wenger is set to sign a new two-year deal at the Emirates.