Venezuela's President Nicolas Maduro gestures while he speaks during a pro-government rally in Caracas, Venezuela August 27, 2016. REUTERS/Carlos Garcia Rawlins

CARACAS (Reuters) - Venezuelan authorities rounded up 25 opposition activists and supporters in the last two days amid plans for a massive protest against President Nicolas Maduro, a rights group said on Wednesday.

Opposition supporters around the country are descending on Caracas for rallies scheduled for Thursday to demand a recall referendum against the unpopular socialist leader. But Maduro, 53, says they are planning violence and a coup.

The local Penal Forum rights group said that of 25 people held in the last 48 hours, 12 had been released while 13 were still in custody by mid-afternoon Wednesday.

While Maduro accuses opposition parties of trying to reprise a 2002 putsch against Chavez, they say the government is carrying out a wave of repression to intimidate them before Thursday’s marches that they have dubbed “Takeover of Caracas”.

It was not clear if those still being held would be charged or if the detentions were preventive to stop them participating in Thursday’s events. Authorities did not immediately respond to queries about the arrests.