The veteran American swimmer Ryan Lochte has been held up at gunpoint at the Rio Olympics, according to reports.

According to Fox Sports, he had been invited to a party by the Brazilian swimmer Thiago Pereira, following the conclusion of the swimming programme on Saturday night. The station reports that the incident happened at the party but Lochte is now safe and back at team headquarters.

Fox quoted Lochte's mother Ileana, who said he had described the incident as "terrifying".

The 32 year-old has won six Olympic gold medals, including his most recent victory as part of the US' 4x200m freestyle team in Rio.