Venezuelan President Nicolas Maduro ordered the expulsion of three US diplomats on Sunday, accusing them of attempting to incite student groups to fight the government.

Mr Maduro charged that Venezuelan intelligence officials who had tailed them for the past two months found evidence they were trying to infiltrate universities under cover of issuing visas.

Triggering the expulsion was the US Obama administration's public support for right-wing opposition leader Leopoldo Lopez, who is being hunted by police after Mr Maduro accused him of leading a "fascist" plot to oust the socialist government.

Mr Maduro said that US State Department official Alex Lee had warned Venezuela's ambassador to the Washington-based Organisation of American States that arresting the former mayor would bring serious negative consequences with international ramifications.

"These are unacceptable, insolent demands," Mr Maduro said during a televised address. "Venezuela doesn't take orders from anyone in the world."

Harvard-educated Mr Lopez has been at the centre of rising tensions in Venezuela since he led a right-wing demonstration against Mr Maduro's government last week.

The government blames him for violence following the rally, when students fought security forces and pro-government groups, leaving three dead.

Mr Maduro called for a march by oil workers today, beginning at the same Caracas plaza where Mr Lopez has said he too will rally supporters.

Mr Lopez announced his plans a few hours before President Maduro's speech, in a video shot at an undisclosed location.

He claimed that he didn't fear arrest and accused authorities of trying to violate his right to protest.

He said he was prepared to turn himself in and answer to an arrest warrant on charges ranging from terrorism and homicide to vandalism.

Security forces raided his home and that of his parents over the weekend, seeking to serve the arrest order, but Mr Lopez was elsewhere.

The Lopez campaign is in conflict not only with the government, but is being mounted in defiance of marginally less right-wing opposition leader Henrique Capriles, who publicly disapproves of the street protests by the opposition's extreme right.