Venezuelan regulators revoked the broadcast rights of 34 radio stations on Friday, deepening a rift between President Hugo Chavez's government and the private media.

Diosdado Cabello, who heads Venezuela's telecommunications regulatory agency, said some of the broadcasters failed to update their registrations or let their concessions expire, while others held licenses granted to an operator who is now deceased.

He said regulators have begun informing the affected radio stations, and they "will have to end transmissions once they are notified."

Chavez's government has clashed increasingly with private media in recent months and is slowly tightening its grip over the industry, raising concerns among watchdog and human rights groups that accuse the government of trying to stifle dissent.

More than 200 other radio stations are also under investigation for failing to update their registrations.

Chavez has said their concessions could be handed over to operators who share his vision for a socialist system in Venezuela.

Regulators have also opened a series of investigations that could lead to the shutdown of opposition-aligned Globovision, the only TV channel fiercely critical of Chavez remaining on the open airwaves.