Film director Roman Polanski is in custody on an arrest warrant from the United States issued in 1977.
Swiss police have confirmed Polanski, 76, was detained over the weekend as he travelled to Switzerland to collect a lifetime achievement award at the Zurich Film Festival.
His work includes films The Pianist, Chinatown, Tess and Rosemary's Baby.
Polanski admitted unlawful sex with a girl, then aged 13 years, in the US in 1977, but fled to France in 1978 before sentencing.
In recent years, he has tried to have the rape case dismissed, but a US judge formally rejected his requests in May.
Polanski was initially indicted on six felony counts and faced up to life in prison. The BBC reports he claims the original judge, who is now dead, arranged a plea bargain but later reneged.
The woman at the centre of the case, Samantha Geimer, has previously asked for the charges to be dropped, saying the continued publication of details "causes harm to me, my husband and children".
The Swiss justice ministry said on Sunday that Polanski was being held under a 2005 international alert issued by the US government related to a 1978 arrest warrant.
The ministry added that will not be sent to the United States until extradition proceedings were complete.