By Girish Gupta

CARACAS (Reuters) - A prominent journalist and lawyer jailed on Venezuela's Margarita island was charged on Monday with money laundering, according to family and a rights group, following his arrest after publicizing a protest against President Nicolas Maduro.

Videos published by activists, purportedly from the locality of Villa Rosa, showed scores of people banging pots and pans and jeering the socialist leader as he visited the island on Friday evening.

More than 30 people were briefly detained, activists said on Saturday.

The incident came as the opposition has been stepping up its campaign for a referendum to recall Maduro, who says a coup is being planned against him.

All those held in Margarita were released after a few hours except Braulio Jatar, 58, who was picked up on Saturday morning on his way to host his regular morning radio show, according to his family.

They knew nothing about his whereabouts until hours later when intelligence agents came to the family home and searched it, allowing them to send him clothes, according to his sister, Boston-based Ana Julia Jatar, 60.

Jatar was born in Chile, where Foreign Minister Heraldo Muñoz expressed concern over Jatar's arrest and the charges against him.

"As a Chilean, he has the right to be protected by the state of Chile and we will take all the steps necessary on his behalf," Munoz told reporters.

On Thursday, hundreds of thousands of people marched peacefully through Caracas to demand the right to vote on a recall of Maduro, the successor to Hugo Chavez, whose popularity has plummeted due to a brutal economic crisis.

Of 163 people detained in relation to Thursday's protests, 29 remain behind bars, according to local rights group Penal Forum. Five of them have been formally charged.

That brings the total of political prisoners in Venezuela to 93, said Alfredo Romero, the director of Penal Forum.

Both Romero and Jatar's sister confirmed the charge of money laundering. They offered no details, saying only that they had been told he would remain under arrest for the time being.

The Ministry of Information did not immediately respond to requests for comment on Jatar's case or other arrests.

Government officials have sought to downplay the incident on Margarita, saying videos had been "manipulated" by pro-opposition media. Showing video clips of their own, they say Maduro was cheered by supporters on his visit to the island.

(Editing by Andrew Cawthorne and James Dalgleish and Tom Brown)