The Inter American Press Association said in a statement Friday night that Wyss had been transferred to Caracas and is being held in solitary confinement.
President Nicolas Maduro did not mention the journalist during a four-hour televised speech.
Wyss was in Venezuela to report on upcoming municipal elections and the chronic shortages of such staples as milk, toilet paper and automobile parts amid an economic crisis.
Economists have blamed the situation on government mismanagement and currency controls set by the late President Hugo Chavez. The government blames the shortages on hoarding and speculation by the private sector, and accuses right-wing agitators and the U.S. government of being behind a destabilization campaign it calls an 'economic war.'"
Journalists have encountered harassment while reporting on the economic crisis. Last week, three reporters for Caracas newspaper Diario 2001 were detained, and one allegedly beaten by police, after witnessing a group of frenzied shoppers break through a barricade to receive a government-provided Christmas food basket.
Government officials have sometimes publicly vilified members of the international media as opponents of the Chavista revolution. On the day in March when Chavez's death was announced, supporters beat a Colombian TV reporter outside the military hospital in Caracas where he was said to have died.
Claudio Paolillo, chairman of a press freedom committee at the Inter American Press Association, said he was bewildered by this "new demonstration of intolerance by a regime that day after day shows its contempt for the work of journalists."