Venezuelan President Hugo Chavez has said he will not renew the licence for the country's second largest TV channel which he says expires in March 2007.
The move has been called a grave violation of freedom of expression
In an address to troops, Mr Chavez said he would not tolerate media outlets working towards a coup against him.
Radio Caracas Television, which is aligned with the opposition, supported a strike against Mr Chavez in 2003.
But the TV's head said there must be some mistake as its licence was not up for renewal in the near future.
Marcel Granier also vowed to fight against the president's plans in Venezuela's courts and on the international stage.
The BBC's Greg Morsbach in Caracas says Mr Chavez has repeatedly threatened to take the TV off the air but has never given a date.
The move could help silence some of his critics in the media who have been a thorn in his side for several years, he says.
Mr Chavez, who was returned to power by a wide margin on 3 December, said Mr Granier was mistaken in believing "that concession is eternal".
"It runs out in March. So it's better that you go and prepare your suitcase and look around for what you're going to do in March," he said during a televised speech to soldiers at a military academy in Caracas.
"There will be no new operating licence for this coupist TV channel called RCTV. The operating licence is over... So go and turn off the equipment," Mr Chavez said.
'Violation of freedom'
Mr Chavez said the channel was "at the service of coups against the people, against the nation, against national independence, against the dignity of the republic".
The channel is among a number of private TV and radio networks that in recent years have strongly criticized Mr Chavez' government and favoured the opposition.
Many media outlets, including RCTV, supported a bungled coup in 2002 and a devastating general strike in 2003 that failed to unseat the president.
The press freedom campaign group, Reporters Without Borders, said the proposed move would be a grave violation of freedom of expression in Venezuela.
RCTV is one of the country's oldest channels and began broadcasting in 1953.